[Federal Register: March 5, 2002 (Volume 67, Number 43)]
[Proposed Rules]
[Page 10049-10085]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05mr02-18]
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Part II
Department of Transportation
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National Highway Traffic Safety Administration
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49 CFR Part 571
Federal Motor Vehicle Safety Standards; Tires; Proposed Rule
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-00-8011]
RIN 2127-AI54
Federal Motor Vehicle Safety Standards; Tires
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The Transportation Recall Enhancement, Accountability, and
Documentation Act of 2000 mandates a rulemaking proceeding to revise
and update our safety performance requirements for tires. In response,
this document proposes to establish new and more stringent tire
performance requirements in a new Federal motor vehicle safety standard
that would apply to all new tires for use on vehicles with a gross
vehicle weight rating of 10,000 pounds or less. The agency recently
proposed to establish a new tire standard, Standard No. 139, in a
December 2001 NPRM on tire safety information. Today's document
proposes to include the new tire performance requirements in that
standard.
This document seeks comments on the proposed new standard,
including its applicability and test procedures, modifications to
related existing standards, and lead time provided for manufacturers to
achieve compliance. It also seeks comments on the possible future
specification of shearography analysis, a technique which evaluates the
condition of a tire using laser technology. Finally, it seeks comments
on NHTSA's research plans.
DATES: You should submit your comments early enough to ensure that
Docket Management receives them not later than May 6, 2002.
ADDRESSES: You may submit your comments in writing to: Docket
Management, Room PL-401, 400 Seventh Street, SW., Washington, DC,
20590. Alternatively, you may submit your comments electronically by
logging onto the Docket Management System website at http://
dms.dot.gov. Click on ``Help & Information'' or ``Help/Info'' to view
instructions for filing your comments electronically. Regardless of how
you submit your comments, you should mention the docket number of this
document.
FOR FURTHER INFORMATION CONTACT: For technical and policy issues: Mr.
George Soodoo or Mr. Joseph Scott, Office of Crash Avoidance Standards,
National Highway Traffic Safety Administration, 400 Seventh Street,
SW., Washington, DC 20590. Telephone: (202) 366-2720. Fax: (202) 366-
4329.
For legal issues: Nancy Bell, Attorney Advisor, Office of the Chief
Counsel, NCC-20, National Highway Traffic Safety Administration, 400
Seventh Street, SW., Washington, DC 20590. Telephone: (202) 366-2992.
Fax: (202) 366-3820.
SUPPLEMENTARY INFORMATION: You may read the materials placed in the
docket for this document (e.g., the comments submitted in response to
this document by other interested persons) by going to the street
address given above under ADDRESSES. The hours of the Docket Management
System (DMS) are indicated above in the same location.
You may also read the materials on the Internet. To do so, take the
following steps:
(1) Go to the Web page of the Department of Transportation DMS
(http://dms.dot.gov/).
(2) On that page, click on ``search'' near the top of the page or
scroll down to the words ``Search the DMS Web'' and click on them.
(3) On the next page (http://dms.dot.gov/search/), scroll down to
``Docket Number'' and type in the four-digit docket number (8011) shown
in the title at the beginning of this document. After typing the docket
number, click on ``search.''
(4) On the next page (``Docket Summary Information''), which
contains docket summary information for the materials in the docket you
selected, scroll down to ``search results'' and click on the desired
materials. You may download the materials.
Table of Contents
I. Executive Summary and Overview
II. Background
III. Existing Tire Standards--Performance Requirements
IV. Current Safety Problem--Outdated Performance Requirements
A. Transition From Bias Ply to Radial Tires
B. Safety Problems Associated with Tires
1. Population of Tire Related Crashes
2. Geographical and Seasonal Effects
3. Tire Problems by Tire Type and Light Truck Type
4. Crashes Indirectly Caused by Tire Problems
C. Implications of Changes in U.S. Light Vehicle Market
V. Agency Response to Safety Problem
A. Relationship Between TREAD Act and Tire Harmonization
B. Submissions to NHTSA Tire Upgrade Docket (Docket No. NHTSA-
2000-8011)
1. Rubber Manufacturers Association December 2000 Testing
Protocol
A. Passenger Tires--High Speed Test
B. Passenger Tires--Endurance Test
C. Light Truck Tires--High Speed
D. Light Truck Tires--Endurance Test
2. Other Substantive Submissions
C. NHTSA Tire Testing at Standards Testing Lab
1. High Speed Testing
2. Endurance Testing
3. Low Inflation Pressure Testing
4. Conclusions From Testing Results
VI. Agency Proposal
A. Summary of Proposal
B. Application of the New Standard
C. Proposed Test Procedures
1. High Speed Test
a. Ambient Temperature
b. Load
c. Inflation Pressure
d. Speed
e. Duration
2. Endurance Test
a. Ambient Temperature
b. Load
c. Inflation Pressure
d. Speed
e. Duration
3. Low Inflation Pressure Performance Tests
a. Low Pressure--Tire Pressure Monitoring System Test
b. Low Pressure--High Speed Test
4. Road Hazard Impact Test
5. Bead Unseating
6. Aging Effects
a. Adhesion (Peel) Test
b. Michelin's Long Term Durability Endurance Test
c. Oven Aging
D. Deletion of FMVSS No. 109
E. Modification to FMVSS Nos. 110 and 120
F. Modification to FMVSS Nos. 117 and 129
G. De-rating of P-metric tires
H. Other NHTSA Research Plans
1. Bead Unseating Research
2. Road Hazard Impact Test (SAE J1981) Research
I. Additional Considerations
1. Lead time
2. Shearography Analysis
3. Revised Test Speed in Uniform Tire Quality Temperature
Grading Requirement
4. Request for Comments on Particular Issues
VII. Benefits
VIII. Costs
A. Original Equipment Tire and Vehicle Costs
B. Total Annual Costs
C. Testing Costs
D. Request for Comments on Costs and Benefits of Individual
Tests
IX. Effective Date
X. Rulemaking Analyses and Notices
A. Executive Order 12866 and DOT Regulatory Policies and
Procedures
B. Regulatory Flexibility Act
C. National Environmental Policy Act
D. Executive Order 13132 (Federalism)
E. Unfunded Mandates Act
F. Civil Justice Reform
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G. National Technology Transfer and Advancement Act
H. Paperwork Reduction Act
I. Plain Language
XI. Submission of Comments
XII. Proposed Regulatory Text
I. Executive Summary and Overview
Section 10 of the Transportation Recall Enhancement,
Accountability, and Documentation (TREAD) Act mandates that the agency
issue a final rule to revise and update its tire performance standards.
However, the Act gives the agency substantial discretion over the
substance of the final rule. The Act does not specify what revisions or
updatings should be made. For example, it does not specify which
particular existing tests should be improved or how much they should be
improved. Likewise, it does not specify which particular new tests
should be added or how stringent they should be. However, the
legislative history does contain specific references to some tests like
aging tests.
In response to section 10, the agency comprehensively examined
possible ways of revising and updating its tire standards. In doing so,
it placed particular emphasis on improving the ability of tires to
withstand the effects of factors mentioned during the consideration and
enactment of the TREAD Act such as tire heat build up, low inflation,
and aging. The agency has examined the value of modifying the existing
tests in its tire standards. In addition, it has examined the value of
adopting several new tests.
As a result of these efforts, the agency has identified an array of
amendments for revising and updating its tire standards and thereby
improving tire performance. Some would upgrade existing tests, while
the others would add new ones.
The agency recently proposed to establish a new tire standard,
Standard No. 139, in a December 2001 NPRM on tire safety information
(Docket No. NHTSA-01-11157, 66 FR 65536, December 19, 2001). Today's
document proposes to include the new tire performance requirements in
that standard. The standard would apply to light vehicle tires. As used
in the December 2001 proposal, ``light vehicles'' are vehicles (except
motorcycles) with a gross vehicle weight rating (GVWR) of 10,000 pounds
or less.
Under today's proposal, the new standard would contain requirements
and test procedures addressing the following aspects of tire
performance: Tire Dimension, High Speed, Endurance, Road Hazard Impact,
Bead Unseating, Low Inflation Pressure, and Aging Effects.\1\
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\1\ See 66 FR 65536 for the proposed tire information
requirements. For the convenience of the reader, we have placed in
the docket for today's NPRM a document that shows how the tire
safety information and performance requirements may appear together
in Standard No. 139.
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The proposed High Speed and Endurance tests would replace the
current High Speed and Endurance tests in FMVSS No. 109, New Pneumatic
Tires--Passenger Cars, 49 CFR 571.109, with a more stringent
combination of testing parameters (ambient temperature, load, inflation
pressure, speed, and duration.) Most significantly, the proposed High
Speed test specifies test speeds (140, 150 and 160 km/h (88, 94, and
100 mph)) that are substantially higher than those currently specified
in FMVSS No. 109 (120, 128, 136 km/h (75, 80, 85 mph)). Likewise, the
proposed Endurance Test specifies a test speed 50 percent faster (120
km/h (75 mph)) than that currently specified in FMVSS No. 109 (80 km/h
(50 mph)), as well as a duration 6 hours longer (40 hours total) than
that currently specified in FMVSS No. 109 (34 hours total). At the
specified test speed (120 km/h), the Proposed Endurance Test distance
(4800 km) is almost double the distance accumulated than under the
current Endurance Test (2720 km at 80 km/h). These new testing
parameters are based on NHTSA's activities undertaken in response to
the TREAD Act, including extensive agency testing, data gathering and
analyses as well as agency review of other existing international,
industry and National standards and proposals, and submissions by the
public.
The proposed Road Hazard Impact Test and the Bead Unseating Test
are modeled on SAE Recommended Practice J1981, Road Hazard Impact Test
for Wheel and Tire Assemblies (Passenger Car, Light Truck, and
Multipurpose Vehicles), and the Toyota Air Loss Test, respectively.
These new tests would replace the Strength and Bead Unseating
Resistance tests in the current FMVSS No. 109 with tests that are more
dynamic as opposed to quasi-static.
In addition to the tests cited above, the proposed standard
contains tests for two new aspects of performance: Low Inflation
Pressure Performance and Aging Effects. By creating tests for these
aspects of performance, the agency is attempting to address concerns
raised by members of Congress in hearings that preceded the enactment
of the TREAD Act that NHTSA's current test requirements do not evaluate
how well tires perform when significantly underinflated or after being
subjected to environmental variables, such as heat, which accelerate
aging. In particular, underinflation and heat were factors highlighted
as contributing to failure of the Firestone ATX and Wilderness tires in
the TREAD hearings, and in the agency's Firestone investigation (NHTSA
Office of Defects Investigation (ODI) investigation number EA00-023).
To test Low Inflation Pressure Performance, the agency is proposing
two alternative tests based on agency testing and data analyses. Both
tests utilize tires significantly under-inflated, for instance 20 psi
for P-metric tires (the low inflation pressure threshold requirement
for warning lamp activation in the proposed Tire Pressure Monitoring
System (TPMS) standard, Docket No. NHTSA-00-8572 (66 FR 38982, July 26,
2001)), as the ``inflation pressure'' testing parameter for standard
load P-metric tires. To test for resistance to Aging Effects, the
agency proposes three alternative tests that would evaluate a tire's
long term durability through methods different than and/or beyond those
required by both the current and the proposed Endurance Test
parameters. The three tests use peel strength testing, long-term
durability endurance requirements, and oven aging, respectively. The
agency solicits comments on which of the two proposed tests for
addressing Low Inflation Pressure Performance, and which of the three
tests proposed for addressing Aging Effects, should be chosen for the
new standard.
In addition to proposing test procedures for the new standard, the
agency also discusses in this document its ongoing and future research
plans on tire safety, and seeks comments on the future use of
shearography analysis (a method of analysis using laser technology) for
evaluating the condition of tires subjected to the proposed testing
procedures and the plans for revising the Uniform Tire Quality Grading
Temperature Grading Requirement testing speeds so that they are
consistent with the test speeds in the proposed High Speed tests.
Finally, the agency discusses revising FMVSS Nos. 110, Tire
selection and rims, for passenger cars, 49 CFR 571.110, and 120, Tire
selection and rims for motor vehicles other than passenger cars, 49 CFR
571.120, to reflect the applicability of the proposed light vehicle
tire standard to vehicles up to 10,000 pounds GVWR, and revising FMVSS
Nos. 117, Retreaded pneumatic tires, 49 CFR 571.117, and 129, New non-
pneumatic tires for passenger cars, 49 CFR 571.129, to replace the
performance tests which reference or mirror those in FMVSS No. 109 with
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those specified in the proposed new light vehicle tire standard.
Wishing to adopt only those amendments that contribute to improved
safety, and mindful of the principles for regulatory decisionmaking set
forth in Executive Order 12866, Regulatory Planning and Review, NHTSA
has examined the benefits and costs of these amendments. Its efforts to
do so, however, have been limited by several factors. Two factors stand
out. One is the limited time allowed by the schedule specified in the
TREAD Act for completing this rulemaking. That has limited the amount
and variety of information that the agency could obtain and testing
that the agency could conduct to examine the effects of different
versions of the amendments under consideration. The other is the
difficulty inherent in crash avoidance rulemakings, stemming from the
multiplicity of the factors contributing to the occurrence of any crash
and the difficulty of ascertaining the relative contribution of each
factor, in linking specific improvements in safety requirements with
specific reductions in crashes and resulting deaths and injuries.
Together, these limitations have made it difficult to assess and
compare the benefits and costs of this rulemaking.
At this time, the agency believes that improving tires will be
beneficial in reducing tire failures and crashes resulting from tire
failures. However, we do not have a good estimate of the extent to
which the improvements will improve safety. We have made an estimate of
the target population--373 fatalities and 9,247 injuries in the target
population. If the improvements needed to pass the high-speed and
endurance tests (estimated to be 22 percent) related directly to an
improvement in safety, the total potential improvement would be 82
lives saved (373* .22) and 2,034 injuries avoided. Since 32.8 percent
of the tires currently do not pass the proposed requirements, the
benefits would be 27 lives saved (373 * 0.22 * 0.328) and 667 injuries
reduced.
The agency emphasizes that not all benefits could be quantified.
Specifically, the agency believes that there will be other, currently
non-quantifiable, benefits from the proposed Aging test and aspects of
the proposal that address the overloading of vehicles. Additionally,
there could be benefits from the proposed Low Inflation Pressure
Performance tests and from the proposed Road Hazard and Bead Unseating
tests.
The agency's estimate of the price increase to improve tires up to
the performance levels required in the High Speed and Endurance tests
is $3 per affected tire. Based on testing, we estimate that about one-
third (32.8 percent) of all tires would need improvements to pass those
two tests. If the cost for these improved tires were spread across the
entire new light vehicle fleet, the average new vehicle price increase
would, we estimate, be $4.09 per vehicle. The overall annual cost of
these tests for new original equipment (64 million tires) and
replacement tires (223 million tires) is estimated at $282 million for
a total of 287 million tires sold annually and the net costs per
equivalent life saved would be about $7.2 million.
We do not anticipate an increase in costs for the proposed Road
Hazard Impact and Bead Unseating tests because our testing indicates
that most of current production tires would pass these tests. The
agency has not conducted sufficient testing of the proposed Aging tests
to anticipate their potential costs. The agency believes, however, that
most manufacturers already perform an aging test. Therefore, it is
likely that the incremental cost of adding an aging test would be
minimal.
With regard to the Low Inflation Pressure Performance tests, one
alternative would provide no added costs because agency testing
indicates that current production tires pass the test. Tires tested to
the other alternative have a higher failure margin. Costs for this test
cannot be characterized by the agency at this point.
The agency is concerned about the overall costs of this rulemaking
and the net costs per equivalent life saved. While the agency believes
that its proposed amendments represent a reasoned proposal that is
based on best currently available information and that would improve
tire safety, it is concerned about the apparent overall costs of those
amendments. The agency is particularly concerned that the cost per
equivalent life saved is significantly higher than that in most NHTSA
vehicle safety rulemakings.
Because of the broad mandate from Congress and the uncertainty
associated with the analysis of benefits and costs, the agency believes
that the most appropriate course of action is for it to seek public
comment on the full array of potential amendments that it has
identified. As a result of this NPRM, the agency anticipates receiving
cost data and other information that will enable it to refine its
assessment of benefits and costs. The agency will then be in a better
position to pick and choose among the proposed amendments. Its
intention is to use that information to fashion a final rule consistent
with the principles of Executive Order 12866.
II. Background
The Transportation Recall Enhancement, Accountability, and
Documentation (TREAD) Act, Pub. L. 106-414, signed into law on November
1, 2000, requires the agency to address numerous vehicle safety matters
through rulemaking. Section 10 of the Act directs the Secretary of
Transportation to conduct a rulemaking to revise and update the tire
safety standards published at 49 CFR 571.109 and 571.119, and to
complete the rulemaking, i.e., issue a final rule, by June 1, 2002.\2\
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\2\ The title of section 10 is ``Endurance and resistance
standards for tires.'' The section reads in full as follows:
The Secretary of Transportation shall conduct a rulemaking to
revise and update the tire standards published at 49 CFR 571.109 and
49 CFR 571.119. The Secretary shall complete the rulemaking under
this section not later than June 1, 2002.
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III. Existing Tire Standards--Performance Requirements
The following discussion summarizes current provisions relating to
tires.
FMVSS No. 109, New pneumatic tires, 49 CFR 571.109, specifies the
requirements for all tires manufactured for use on passenger cars
manufactured after 1948. This standard, which was issued in 1967 under
the National Traffic and Motor Vehicle Safety Act (Safety Act),
specifies dimensions for tires used on passenger cars and requires that
the tires meet specified strength, resistance to bead unseating,
endurance, and high speed requirements, and be labeled with certain
safety information. FMVSS No. 109 applies to passenger car (P-metric)
tires produced for use on passenger cars, multipurpose passenger
vehicles (MPV), and light trucks (sport utility vehicles (SUV), vans,
minivans, and pickup trucks). The standard was adopted from the Society
of Automotive Engineers (SAE) recommended practice J918c, Passenger Car
Tire Performance Requirements and Test Procedures, which was first
issued by the SAE in June 1965. \3\ The current FMVSS No. 109 includes
four performance requirements for tires:
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\3\ SAE is an organization which develops voluntary standards
for aerospace, automotive and other industries. Many of SAE's
recommended practices are developed using technical information
supplied by vehicle manufacturers and automotive test laboratories.
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A strength test, which evaluates the strength of the
reinforcing materials in the tire;
A resistance-to-bead unseating test, which evaluates how
well the tire bead
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is seated on the rim (regulating the tire-rim interface guards against
sudden loss of tire air pressure when a tire is subjected to lateral
forces such as during severe turning maneuvers);
An endurance test, which evaluates resistance to heat
buildup when the tire is run at its rated load nonstop for a total of
34 hours, and
A high speed test, which evaluates resistance to heat
buildup when the tire is run at 88 percent of its maximum load at
speeds of 75 mph, 80 mph, and 85 mph for 30 minutes at each speed.
For the purposes of testing tires to determine their compliance
with these requirements, the standard specifies values for several
factors, such as tire inflation pressure, the load \4\ on the tire, and
the rim on which a tire is mounted. The standard specifies permissible
inflation pressures (or wheel sizes, in the case of bead unseating
test) to facilitate compliance testing. The standard requires that each
passenger car tire must have a maximum permissible inflation pressure
labeled on its sidewall (S4.3). Section 4.2.1(b) lists the permissible
maximum pressures: 32, 36, 40, or 60 pounds per square inch (psi) or
240, 280, 290, 300, 330, 340, 350, or 390 kiloPascals (kPa). A
manufacturer's selection of a maximum pressure has the effect of
determining the pressures at which its tire is tested. For each
permissible maximum pressure, Table II of the standard specifies
pressures at which the standard's tests must be conducted. The intent
of this provision is to limit the number of possible maximum inflation
pressures and thereby reduce the likelihood of having tires of the same
size on the same vehicle with one maximum load value, but with
different maximum permissible inflation pressures.
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\4\ Load percentages stated throughout this document, unless
otherwise specified, are based on the sidewall maximum rated load.
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Closely related to FMVSS No. 109 is FMVSS No. 110, Tire selection
and rims, 49 CFR 571.110. FMVSS No. 110 requires that each passenger
car be equipped with tires that comply with FMVSS No. 109, that tires
on the cars be capable of carrying the GVWR of that vehicle, that the
rims on the car be appropriate for use with the tires, and that certain
information about the car and its tires appear on a placard in the
passenger car. FMVSS No. 110 also specifies rim dimension requirements
and further specifies that, in the event of a sudden loss of inflation
pressure at a speed of 97 km/h (60 mph), rims must retain a deflated
tire until the vehicle can be stopped with a controlled braking
application. FMVSS No. 110 initially became effective in April 1968.
FMVSS No. 117, Retreaded pneumatic tires, 49 CFR 571.117,
establishes performance, labeling, and certification requirements for
retreaded pneumatic passenger car tires. Among other things, the
standard requires retreaded passenger car tires to comply with the
tubeless tire resistance to bead unseating and the tire strength
requirements of FMVSS No. 109. FMVSS No. 117 also specifies
requirements for casings to be used for retreading, and certification
and labeling requirements.
FMVSS No. 119, New pneumatic tires for vehicles other than
passenger cars, 49 CFR 571.119, specifies performance and labeling
requirements for new pneumatic tires designed for highway use on
multipurpose passenger vehicles, trucks, buses, trailers and
motorcycles manufactured after 1948, and which requires treadwear
indicators in tires, and rim matching information concerning those
tires. Under this standard, each tire has to meet requirements that are
qualitatively similar to those in FMVSS No. 109 for passenger car
tires. The high speed performance test in this standard only applies to
motorcycle tires and to non-speed-restricted tires of 14.5-inch nominal
rim diameter or less marked load range A, B, C, or D. In addition,
FMVSS No. 119 does not contain a resistance-to-bead unseating test.
A tire under FMVSS No. 119 is generally required to meet the
performance requirements when mounted on any rim listed as suitable for
its size designation in the publications, current at the time of the
tire's manufacture, of the tire and rim associations that are listed in
the standard. Further, the tire is required to meet the dimensional
requirements when mounted on any such rim of the width listed in the
load-inflation tables of this standard. In addition to the permanent
marking for any non-matching listed rims, each tire manufacturer is
required to attach to the tire, for the information of distributors,
dealers and users, a label listing the designations of rims appropriate
for use with the tire.
FMVSS No. 120, Tire Selection and rims for motor vehicles other
than passenger cars, 49 CFR 571.120, requires that vehicles other than
passenger cars equipped with pneumatic tires be equipped with rims that
are listed by the tire manufacturer as suitable for use with those
tires and that rims be labeled with certain information. It also
requires that these vehicles shall be equipped with tires and rims that
are adequate to support the fully-loaded vehicle under contemplated
operating conditions.
The primary effect of Standard No. 120 is to specify the minimum
load-carrying characteristics of tires not already subject to the
passenger car tire and rim selection requirements of FMVSS No. 110.
Tire selection under FMVSS No. 120 consists of two elements. With
one exception, each vehicle must be equipped with tires that comply
with FMVSS No. 119 and the load rating of those tires on each axle of
the vehicle must together at least equal the gross axle weight rating
(GAWR) for that axle. If the certification label lists more than one
GAWR-tire combination for the axle, the sum of the tire's maximum load
ratings must meet or exceed the GAWR that corresponds to the tire's
size designation. If more than one combination is listed, but the size
designation of the actual tires on the vehicle is not among those
listed, then the sum of the load ratings must simply meet or exceed the
lowest GAWR that does appear.
FMVSS No. 120 also contains a requirement related to the use of
passenger car tires on vehicles other than passenger cars. The
requirement states that when a tire that is subject to FMVSS No. 109 is
installed on a multipurpose passenger vehicle, truck, bus, or trailer,
the tire's load rating must be reduced by a factor of 1.10 by dividing
by 1.10 before determining whether the tires on an axle are adequate
for the GAWR. This 10 percent de-rating of P-metric tires provides a
greater load reserve when these tires are installed on vehicles other
than passenger cars. The reduction in the load rating is intended to
provide a safety margin for the generally harsher treatment, such as
heavier loading and possible off-road use, that passenger car tires
receive when installed on a MPV, truck, bus or trailer, instead of on a
passenger car.
FMVSS No. 129, New non-pneumatic tires for passenger cars, 49 CFR
571.129, includes definitions relevant to non-pneumatic tires and
specifies performance requirements, testing procedures, and labeling
requirements for these tires. To regulate performance, the standard
contains performance requirements and tests related to physical
dimensions, lateral strength, strength (in vertical loading), tire
endurance, and high speed performance. The performance requirements and
tests in FMVSS No. 129 were based upon those contained in FMVSS No.
109.
The FMVSS No. 129 labeling requirements are similar to those set
[[Page 10054]]
forth in section S4.3 of FMVSS No. 109 for size, designation, load,
rating, rim size and type designation, manufacturer or brand name,
certification, and tire identification number. The standard also
includes temporary use and maximum speed labeling requirements and
allows methods of permanent marking other than ``molding'' in
anticipation of the difficulty of molding required information on non-
pneumatic designs. FMVSS No. 129 initially became effective in August
1990.
IV. Current Safety Problem--Outdated Performance Requirements
A. Transition From Bias Ply to Radial Tires
When FMVSS No. 109 was issued in 1967, nearly all (more than 99
percent) of passenger car tires in the U.S. were of bias, or bias belt
construction. The test procedures that appear in FMVSS No. 109 were
developed in a bias tire environment. Today, bias tires have been
almost completely replaced by radial tires on passenger cars. The use
of radial tires has grown to the extent that they represent more than
95 percent of passenger tires in both the U.S. and Europe and are used
on most new light vehicles sold in the U.S.\5\ NHTSA does not require
radial tires, but regulates their performance through FMVSS Nos. 109
and 119.
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\5\ Statistics relating to the increase in use of radial tires
since 1968, as reported in the Rubber Manufacturers Association's
(RMA's) Factbook 2000--U.S. Tire Shipment Activity Report for
Statistical Year 1999 (RMA 2000 Yearbook), are as follows:
OE Passenger Tires Shipments: (included are all P-
metric tires even if destined for light truck usage) In 1970 radial
tires comprised 0.5 percent of the market and bias/bias ply tires
comprised 99.5 percent. In 1999 radial tires comprised 93.7 percent
of the market and bias/bias ply tires comprised 6.3 percent.
Replacement Market Passenger Tire Shipments:
(Replacement shipments include all domestically produced and
imported tires sent to the U.S. replacement market. Figures include
all sizes and types of tires designed for standard highway passenger
car service, including P-Metric tires destined for light trucks.) In
1970 radials comprised 2.1 percent of market and in 1999 radials
comprised 99.8 percent of market.
Production of Passenger Tires: (Passenger tire
production covers all tires produced in the United States whether
for domestic consumption or for export. Figures represent the
production for all sizes and types of tires designed for standard
highway passenger car service and include P-Metric tires destined
for use on light trucks.) In 1970 radial tires comprised 0.0 percent
of tires produced. In 1999 radial tires comprised 99.1 percent of
tires produced.
OE Light Truck Tires Shipments: (Light truck tire
original equipment shipments covers all tires sent to manufacturers
or original equipment vehicles in the U.S. and includes all sizes/
types of tires designed by the participants for fitment to light
truck.) In 1980 radial tires comprised 14.8 percent of shipments and
in 1999 radial tires comprised 98.3 percent of shipments.
Replacement Light Truck Tires Shipments: (Light truck
tire replacement shipments designates all tire shipments sent for
replacement purposes to the domestic tire market in the U.S. and
includes all sizes/types of tires designed by the participants for
fitment to light truck.) In 1980 radials comprised 9.9 percent of
shipments and in 1999 radials comprised 94.5 percent of shipments.
Production of Light Truck Tires: (Tires produced in US
whether for domestic consumption or for export outside the United
States--does not include P-metric tires). In 1980 radials comprised
7.1 percent of production and in 1999 radials comprised 98.7 percent
of production.
---------------------------------------------------------------------------
Radial tires are less susceptible than bias ply tires to most types
of failures. Also, radial tire design resulted in significant
improvements in tire performance compared with bias ply tires, thus
making it easier for radial tires to comply with the requirements of
FMVSS No. 109 than for bias tires.
A bias passenger car tire carcass is typically made up of two or
four plies of cord material that run from bead to bead at an angle of
approximately 35 degrees to the centerline of the tire. Alternating
plies are applied at alternating angles during tire manufacture so that
the cord paths of alternating plies criss-cross. This type of
construction provides a very strong, durable carcass for the tire.
However, it has drawbacks. Because the ply cords criss-cross and all
the cords are anchored to the beads, the carcass is stiff and
relatively inflexible. This type of construction prevents different
parts of the tire from acting independently of one another when forces
are applied to the tire. As a result, a bias construction is
susceptible to impact breaks because it does not easily absorb road
irregularities.
By comparison, a radial passenger car tire carcass is typically
made up of one or two plies of cord material that run from bead to bead
at an angle of approximately 90 degrees to the centerline of the tire.
As a result, the cords do not criss-cross. Because the cords do not
criss-cross and because the opposite ends of each cord are anchored to
the beads at points that are directly opposite to each other, the
radial tire carcass is very flexible. The radial tire is reinforced and
stabilized by a belt that runs circumferentially around the tire under
the tread. This construction allows the sidewalls to act independently
of the belt and tread area when forces are applied to the tire. This
``independent'' action is what allows the sidewalls to readily absorb
road irregularities without overstressing the cords. Impact breaks
caused by cord rupture do not occur in radial-ply passenger car tires.
This ``independent'' action also allows two important things to happen
during cornering: (1) The tread of a radial tire remains fully in
contact with the road over the entire tread width, and (2) the ply
cords and sidewall are able to absorb the cornering forces without
exerting the twisting force on the beads that are exerted by bias
constructions.
These characteristics of a radial tire construction are what make
the existing high speed test, endurance test, strength test \6\, and
bead-unseating test appear to be ineffective in differentiating among
today's radial tires with respect to these aspects of performance.
---------------------------------------------------------------------------
\6\ The FMVSS 109 plunger energy or strength test was designed
to evaluate the strength of the reinforcing materials in bias ply
tires, typically rayon, nylon or polyester, and it continues to
serve a purpose for these tires. However, a radial tire is not
susceptible to the kind of failure for which this test was designed
to prevent. The flexible sidewalls of radial tires easily absorb the
shock of road irregularities.
Because of the belt package, radial tires far exceed the
strength requirements of the test and many times the plunger bottoms
out on the rim instead of breaking the reinforcing materials in the
radial tire. During the years 1996 through 1998 RMA members reported
conducting nearly 19,000 plunger energy (strength) tests on radial
tires. There were no reported failures.
---------------------------------------------------------------------------
B. Safety Problems Associated With Tires
Tire under-inflation, high ambient temperatures, and vehicle load
are among the factors being considered in the ongoing evaluation of the
radial tire failures that have occurred in recent years. Data
concerning tire failure, blowouts, and rollovers are discussed below.
1. Population of Tire Related Crashes
Several crash files contain information on ``general'' tire related
problems that precipitate crashes. These files are the National
Automotive Sampling System--Crashworthiness Data System (NASS-CDS) \7\
and the Fatality Analysis Reporting System (FARS).\8\
---------------------------------------------------------------------------
\7\ For the NASS-CDS system, trained investigators collect data
on a sample of tow-away crashes around the country. These data can
be ``weighted up'' to national estimates. A NASS-CDS General Vehicle
Form contains the following information: A critical pre-crash event,
such as vehicle loss of control due to a blowout or flat tire. This
category includes only part of the tire-related problems which cause
crashes. This coding would only be used when the tire went flat or
there was a blowout that caused a loss of control of the vehicle,
resulting in a crash.
\8\ In FARS, tire problems are noted after the crash, if they
are noted at all. The FARS file does not indicate whether the tire
problem caused the crash, influenced the severity of the crash, or
just occurred during the crash. For example, some crashes may have
been caused by a tire blowout, while in others the vehicle may have
slid sideways and struck a curb, causing a flat tire which may or
may not have influenced whether the vehicle experienced rollover.
Thus, while an indication of a tire problem in the FARS file give
some indication as to the potential magnitude of the tire problem in
fatal crashes, it can neither be considered the lowest possible
number because the tire might not have caused the crash, nor the
highest number of cases because not all crashes with tire problems
might have been coded by the police.
---------------------------------------------------------------------------
[[Page 10055]]
NASS-CDS data for 1995 through 1998 indicate that there are an
estimated 23,464 tow-away crashes per year caused by blowouts or flat
tires.
Estimated Annual Average Number (1995-98 NASS) and Rates of Blowouts or
Flat Tires Causing Tow-away Crashes
------------------------------------------------------------------------
Tire related Percent tire
cases related
------------------------------------------------------------------------
Passenger Cars Total.................... 10,169 0.31
Rollover............................ 1,837 (18%) 1.87
Non-rollover........................ 8,332 (82%) 0.26
Light Trucks Total...................... 13,294 0.99
Rollover............................ 9,577 (72%) 6.88
Non-rollover........................ 3,717 (28%) 0.31
Light Vehicles Total.................... 23,463 0.51
Rollover............................ 11,414 (49%) 4.81
Non-rollover........................ 12,049 (51%) 0.28
------------------------------------------------------------------------
Therefore, about one half of one percent of all crashes are caused
by these tire problems. The rate of blowout-caused crashes for light
trucks (0.99 percent) is more than three times the rate of those
crashes for passenger cars (0.31 percent). Blowouts cause a much higher
proportion of rollover crashes (4.81) than non-rollover crashes (0.28);
and again more than three times the rate in light trucks (6.88 percent)
than in passenger cars (1.87 percent).
FARS data for 1995 through 1998 show that 1.10 percent of all light
vehicles in fatal crashes were coded with tire problems. Light trucks
had slightly higher rates of tire problems (1.20 percent) than
passenger cars (1.04 percent). The annual average number of vehicles
with tire problems in FARS was 535 (313 passenger cars and 222 light
trucks).
2. Geographical and Seasonal Effects
The agency further examined the FARS data to determine whether heat
is a factor in tire problems. We examined two surrogates for heat: (1)
The region of the U.S. in which the crash occurred, and (2) the season
in which the crash occurred. The highest rates of tire problems
occurred in light trucks in southern states in the summertime, followed
by light trucks in northern states in the summertime, and then by
passenger cars in southern states in the summertime. The lowest rates
occurred in winter and fall.
Geographical and Seasonal Analysis of Tire Problems (Percent of Vehicles) in FARS With Tire Problems
----------------------------------------------------------------------------------------------------------------
All light
Passenger cars Light trucks vehicles
(percent) (percent) (percent)
----------------------------------------------------------------------------------------------------------------
Northern States:
Winter................................................ 1.01 0.80 0.94
Spring................................................ 1.12 1.01 1.08
Summer................................................ 0.98 1.46 1.15
Fall.................................................. 1.04 0.93 1.00
Southern States:
Winter................................................ 0.87 0.99 0.92
Spring................................................ 1.09 1.27 1.16
Summer................................................ 1.31 1.99 1.59
Fall.................................................. 0.89 1.07 1.00
----------------------------------------------------------------------------------------------------------------
Winter = December, January, February; Spring = March, April, May; Summer = June, July, August; Fall = September,
October, November.
Southern States = AZ, NM, OK, TX, AR, LA, KY, TN, NC, SC, GA, AL, MS, and FL; Northern States = all others.
Based on these data, tires on light trucks appear to be more
affected by higher ambient temperatures than tires on passenger cars.
3. Tire Problems by Tire Type and Light Truck Type
The agency also examined tire problems in the NASS-CDS from 1992 to
1999 by types of light trucks and vehicle size to determine whether LT
tires used on light trucks exhibited more problems than P-metric tires.
LT tires are used on vehicle classes identified for this analysis as
Van Large B and Pickup Large B groups of vehicles. These groups of
vehicles typically represent the 3/4 ton and 1-ton vans and pick-ups.
P-metric tires are used on most of the other light trucks. The data
indicate that the average percentage of light trucks in the NASS-CDS
having a LT tire problem is 0.84 (10/1,186), while the average percent
of light trucks having a P-metric tire problem is 0.47 percent (53/
11,226).
---------------------------------------------------------------------------
\9\ Unweighted numbers are used because NASS data broken into
small numbers of cells results in weighted numbers which do not
appear logical.
[[Page 10056]]
Tire Problems by Light Truck Vehicle Type 1992 to 1999 NASS-CDS
Unweighted Data 9
------------------------------------------------------------------------
No. of Percent of
cases with Total No. cases with
Light truck type a tire of cases a tire
problem problem
------------------------------------------------------------------------
Van--Compact..................... 11 2,125 0.52
Van--Large A..................... 3 431 0.70
Van--Large B..................... 4 501 0.80
Pickup--Compact.................. 13 3,155 0.41
Pickup--Large A.................. 7 1,849 0.38
Pickup--Large B.................. 6 685 0.88
SUV--Compact..................... 16 3,147 0.51
SUV--Large....................... 3 519 0.58
--------------------------------------
Total........................ 63 12,412 0.51
------------------------------------------------------------------------
The Van--Large A group includes vehicles such as the Ford Econoline 150.
The Van--Large B group includes vehicles such as the Ford Econoline 250/
350.
The Pickup--Large A group includes vehicles such as the Ford F 150.
The Pickup--Large B group includes vehicles such as the Ford F 250/350.
These larger Pickups and vans, however, are also vehicles that
carry heavier loads and are more likely to be more overloaded than
lighter trucks. In addition, these heavier vehicles are often used at
construction sites and may be more apt to encounter nail punctures and
experience flat tires. Thus, there may be usage issues that increase
the percentage of tire problems for these larger trucks, rather than
exclusively a qualitative difference between P-metric and LT tires.
4. Crashes Indirectly Caused by Tire Problems
While the agency has not attempted to estimate the extent to which
improved tires would reduce the chance of having a flat tire it has
looked at crashes indirectly caused by or involved with tire problems.
The agency has identified several types of such crashes. For
instance, if a driver stops his vehicle on the side of the road due to
a flat tire, curious passing drivers often slow down to view the
incident. This can cause congestion, potentially resulting in a rear
impact involving two or more of the passing vehicles toward the rear of
the congested traffic. Another crash type indirectly caused by tire
problems involves tire repair on the shoulder of the road. Sometimes
drivers repairing tires or seeking assistance due to tire problems are
struck, as pedestrians, by other vehicles. These phenomena are not
captured in NHTSA's data files. However, Pennsylvania, Washington, and
Ohio have data files that allow for combining and search for codes for
this phenomena; for instance, searching simultaneously for ``Flat tire
or blowout'' and ``Playing or working on a vehicle'' and
``Pedestrians.'' Our examination of these files for calendar year 1999
for Ohio and Pennsylvania and 1996 for Washington showed the following
information:
State Data on Tire Problems and Pedestrians
------------------------------------------------------------------------
Ohio Washington Pennsylvania
------------------------------------------------------------------------
Pedestrians Injured............... 3,685 2,068 5,226
Pedestrians Injured While Playing 50 (1.4%) 27 (1.3%) 56 (1.1%)
or Working on Vehicle............
Pedestrians Injured While Working 0 2 0
on Vehicle with Tire Problem.....
-------------------------------------
Total crashes................. 385,704 140,215 144,169
------------------------------------------------------------------------
The combined percentage of total crashes with tire problems in
these three states (3,100/670,088 = 0.46) is consistent with the NASS-
CDS data percentage of 0.51 percent. The portion of pedestrians coded
as being injured while working on a vehicle with tire problems is 2/
10,979 = 0.018 percent. Applying this to the estimated number of
pedestrians injured annually across the U.S. (85,000 from NASS-GES)
results in an estimated 15 pedestrians injured per year. The agency,
however, does not have data to estimate how many pedestrian injuries
could be reduced by having better tires.
C. Implications of Changes in U.S. Light Vehicle Market
Sales of light trucks have risen steadily for over the past 20
years and now account for almost half of the U.S. light vehicle
market--more than twice their market share as recently as 1983.
(Industries in Transition, 1/01/00; Journal of Transportation and
Statistics, December 2000.) While 9.0 million passenger cars were sold
in 2000, the consumer preference for light truck vehicles continued to
grow, with sales reaching approximately 8.4 million units, just short
of parity with passenger car sales. (Automotive News 2001 Market Data
Book). According to analysts and manufacturers, sales of light trucks
are expected to surpass sales of cars by approximately 100,000 units
this year and the light truck segment is likely to reach ``around 60%''
before stabilizing. (Auto & Truck Manufacturers Industry Report, 5/15/
00).
In addition to purchasing more SUVs, Americans have shifted toward
a significantly higher use of minivans, pickup trucks, and SUVs for
personal travel. (Journal of Transportation and Statistics, December
2000). The 1995 Nationwide Personal Transportation Survey (NPTS) data
set suggests that the average light duty truck (LDT) (pickup trucks,
SUVs, and minivans) is used over longer distances and with more
[[Page 10057]]
people aboard than passenger cars.\10\ Additionally, SUVs are popular
for long distance weekend travel.
---------------------------------------------------------------------------
\10\ Passenger cars average 12,258 miles per year during the
first 6 years after purchase, while light trucks average 12,683
miles per year during the same time period. NPTS data also indicates
that minivans make the most person-trips per day, followed by SUVs,
passenger cars, and finally pickups. SUVs are estimated to make, on
average, 4.6% more person-trips per day than passenger cars.
---------------------------------------------------------------------------
Approximately 90 percent of these light trucks use passenger car
(P-metric) tires. The other 10 percent use load range C, D, or E tires
which are LT tires and are typically used on heavier light trucks with
a gross vehicle weight rating (GVWR) between 6,000 and 10,000
pounds.\11\ Sales growth of heavier light trucks, those that have GVWRs
above 6,000 pounds, increased at a much faster rate than their lighter
counterparts, with larger SUVs (6,000-10,000 pounds GVWR) showing an
average increase of 38 percent annually between 1990 and 1998.
---------------------------------------------------------------------------
\11\ The net impact on original equipment passenger car tire
shipments in 1999 reflects an increase of 3.9 million units for a
record total of 61 million units, or a 6.8 percent growth over
1998's figure of 57.1 million units. Continued growth in the sales
and production of light truck vehicles also drove the number of
original equipment light truck (LT) tires to a record high of
approximately 8.4 million units or a 25.2 percent increase over
1998's figures. (RMA 2000 Yearbook)
---------------------------------------------------------------------------
V. Agency Response to Safety Problem
A. Relationship Between TREAD Act and Tire Harmonization (Work in UN/
ECE's World Forum for Harmonization of Vehicle Regulations (WP.29))
Prior to this rulemaking, NHTSA embarked on a program of global
harmonization for light vehicle tire standards under the auspices of
the United Nations/Economic Commission for Europe's (UN/ECE) World
Forum for Harmonization of Vehicle Regulations (WP.29).\12\ NHTSA,
within the WP.29's Working Party on Brakes and Running Gear (GRRF),\13\
has been working cooperatively with other countries to develop a global
tire standard that could better assess the safety performance of modern
tires.
---------------------------------------------------------------------------
\12\ Formerly, ``Working Party on the Construction of Vehicles
(WP.29).'' The Forum's website is
http://www.unece.org/trans/main/welcwp29.htm
\13\ The GRRF is a Working Party within WP.29 which is
responsible for developing draft global technical regulations on
brakes, tires, wheels, and other chassis components of motor
vehicles.
---------------------------------------------------------------------------
In July 1999, NHTSA participated in a GRRF meeting in London,
England which initiated deliberations to develop a global technical
regulation for tires with other countries. An industry developed
standard, Global Tire Standard 2000 for New Pneumatic Car Tires (GTS-
2000),\14\ was used as a basis for initial discussions on harmonization
at that meeting. GTS-2000 would substitute a single high-speed test for
the four performance tests in FMVSS No. 109 for most radial tires.\15\
More specifically, GTS-2000 would replace the current FMVSS No. 109
high speed test with the high-speed test required by ECE-R30 (the
European tire regulation for tires used on light passenger vehicles),
including temporary spares. It would also limit the application of the
other three tests currently required by FMVSS No. 109, namely the
strength test, the bead unseating test, and the endurance test, to bias
tires and low speed rated radial tires because industry believes that
these three tests have relevance to bias and bias-belted tires, but
little, if any, relevance to radial tires, with the single exception of
the endurance test for low speed (160 km/h/99 mph, or less) radial
tires.
---------------------------------------------------------------------------
\14\ On January 25, 1999, the Rubber Manufacturers Association
(RMA), along with five other petitioners, submitted a petition
requesting the agency to begin a rulemaking proceeding to amend
FMVSS No. 109 by adopting a new standard. According to the
petitioners, GTS-2000 is a suggestion for a harmonized standard that
the tire industry believes incorporates the best safety practices,
including those from the U.S., Europe, Japan, China, and Australia.
On June 8, 1999, NHTSA granted this petition.
\15\ As described by RMA, GTS-2000 lists the following test
criteria: (1) Physical dimensions for overall width and outer
diameter; (2) strength test (plunger energy) for bias ply and bias-
belted tires; (3) bead unseating resistance tests for bias-ply and
bias-belted tires; (4) low speed (not less than 50 mph) endurance
tests for bias-ply and bias belted tires plus all radial tires with
a speed symbol of Q or below; and (5) high speed endurance tests for
all tires (bias-ply, bias-belted, and radial). In addition, it
contains labeling requirements covering tire pressure, load rating
and tire construction.
---------------------------------------------------------------------------
Since the July 1999 meeting, the GRRF has been considering a draft
global technical regulation (GTR). Prior to the enactment of the TREAD
Act, tentative consensus within an ad hoc tire harmonization working
group of the GRRF concerning the draft GTR had been reached on the
following issues: (1) To adopt the ECE R30 high speed test
methodology\16\ in place of the FMVSS 109 high speed test, (2) to keep
the current FMVSS 109 resistance-to-bead unseating test until NHTSA
develops an alternative that is more appropriate for radial tires, and
(3) to develop an optional requirement for testing wet grip. Other
issues also under discussion in the ad hoc group prior to the TREAD Act
included: (a) the U.S.'s suggestion to lower the inflation pressures in
and increase the duration of the high speed test (current ECE R30
test), (b) the U.S.'s suggestion to agree on the need for tire labeling
requirements that are unique to the U.S., such as maximum inflation
pressure, and UTQG consumer information, (c) the U.S.'s suggestion to
identify requirements that should be included as optional requirements,
(d) assigning to the UN the responsibility for tire plant code
registration for a global standard, and (e) the U.S.'s suggestion to
increase the ambient temperature for the high speed test.
---------------------------------------------------------------------------
\16\ The ECE Regulation 30 includes a single performance
requirement, the high speed test, which is conducted at a speed
close to and up to the rated speed of the tire. The methodology used
in ECE R30 and suggested by the tire industry in GTS-2000 for tire
harmonization determines the test speed based on the tire's speed
symbol rated speed. The following chart illustrates the rated speed
in km/h for each speed symbol.
Speed symbol and Rated Speed--km/h:
F--80
G--90
J--100
K--110
L--120
M--130
N--140
P--150
Q--160
R--170
S--180
T--190
U--200
H--210
V--240
W--270
Y--300
ZR-->300
These speeds range from a minimum of 140 km/h (88 mph) to 300
km/h (188 mph) for W, Y categories. The total test time is 50
minutes. The inflation pressures for the ECE R30 high speed test are
typically much higher than those recommended by vehicle
manufacturers for vehicle operation.
---------------------------------------------------------------------------
In a February 2001 submission to the docket (Docket No. NHTSA-2000-
8011), the Chairman of the GRRF Tire Harmonization Working Group
recommended on behalf of the GRRF that NHTSA adopt a draft text that
reflects the current state of deliberations for developing a harmonized
tire standard.
B. Submissions to NHTSA Tire Upgrade Docket (Docket No. NHTSA-2000-
8011)
In September 2000, NHTSA opened a docket, NHTSA-2000-8011, entitled
``Tire Testing--Federal Motor Vehicle Safety Standard (FMVSS 109).''
The purpose of this docket was to collect tire test data and receive
feedback on its high speed and endurance performance testing matrices.
As of the issuance of this document, comments and recommendations
from 7 entities have been received in the docket. Substantive comments
and recommendations in response to NHTSA's testing matrices are
discussed below. Additionally, Toyota Motor Company (Toyota) submitted
a copy of its Air Loss Test Procedure.
[[Page 10058]]
1. RMA December 2000 Testing Protocol
In December 2000, RMA presented to NHTSA a test protocol (RMA 2000)
that was designed and administered with the participation of the
following tire companies: Bridgestone/Firestone, Continental/General,
Cooper Tire and Rubber, Michelin, Goodyear, Pirelli, Yokohama. The test
protocol is divided into the following principal parts: Passenger Car
Tire High Speed, Passenger Car Tire Endurance, Light Truck High Speed,
and Light Truck Tire Endurance. One hundred thirty-two tests on
approximately 900 tires were included in this protocol. A brief summary
of RMA 2000's conclusions and recommendations are discussed below.
a. Passenger Tires--High Speed Test
RMA 2000 concluded that
[t]he SAE test [J1561] conditions were found to be the most
consistent discriminators required for completion of the rated speed
within the customary one-hour duration.\17\ Test inflation pressure
had the greatest effect in determining completion of the rated
speed. Maximum load was also shown to have an effect on performance,
although not as great as inflation.
---------------------------------------------------------------------------
\17\ The SAE J1561 Test parameters, which are also consistent
with International Standards Organization (ISO) 10191 testing
conditions, are as follows:
(1) Test speed and duration: (ITS = Tire's rated speed minus 40
km/h), 6 speed steps, each 10 min in duration: (1) 0 to ITS, (2)
ITS, (3) ITS + 10 km/h, (4) ITS + 20 km/h, (5) ITS + 30 km/h, (6)
ITS + 40 km/h.
(2) Inflation pressure: 240, 260, 280, 300, or 320 kPa based on
speed rating.
(3) Load: 80 percent.
(4) Ambient Temperature: 38 deg. C.
RMA 2000 recommended that the agency revise the High Speed
Performance test in FMVSS No. 109 to reflect the conditions found in
SAE J1561:
(1) Test speed and duration: (Initial Test Speed (ITS) = Tire's
rated speed minus 40 km/h), 6 speed steps, each 10 min in duration: (1)
0 to ITS, (2) ITS, (3) ITS + 10 km/h, (4) ITS + 20 km/h, (5) ITS + 30
km/h, (6) ITS + 40 km/h.\18\
---------------------------------------------------------------------------
\18\ The following chart illustrates the rated speed in km/h for
each speed symbol. ``ZR'' is an open ended speed category for tires
with a maximum speed capability above 240 km/h, but is also used
specifically for tires having a maximum speed capability above 300
km/h.
Speed symbol and rated speed--km/h:
F--80
G--90
J--100
K--110
L--120
M--130
N--140
P--150
Q--160
R--170
S--180
T--190
U--200
H--210
V--240
W--270
Y--300
ZR--> 300
---------------------------------------------------------------------------
(2) Inflation pressures (kPa): 240 for speed rating through N, 260
for P, Q, R, & S, 280 for T, U, & H, 300 for V & Z, 320 for W & Y.
(3) Load and ambient temperature: 80 percent of maximum rated load,
38 deg.C 3 deg.C.
b. Passenger Tires--Endurance Test
RMA concluded that ``the results seem to indicate that speed,
followed closely by inflation pressure, are key determinants affecting
the number of hours to failure.''
RMA recommended revising the Endurance test in FMVSS No. 109 to
include the following parameters:
(1) Inflation pressure: 180 kPa.
(2) Test speed: constant at 120 Km/h.
(3) Duration and load: 8 hours at 85 percent of maximum rated load,
8 hours at 90 percent of maximum rated load, 8 hours at 100 percent of
maximum rated load.
(4) Ambient temperature: 38 deg.C 3 deg.C.
c. Light Truck Tires--High Speed Test
RMA concluded that
[f]or load range C tires an analysis of the results shows the
maximum load conditions of 90 percent to be more realistic than the
80 percent. Also, it appears that the inflation pressure of 350 kPa
is the most suitable for this test. For load range E tires the data
showed that conditions of 90 percent maximum load and 550 kPa
pressure, while not particularly discerning for the Q speed rated
tires did become much more rigorous for the R speed rated tires (no
S rated tires were included in the load range E tests).
RMA recommended that NHTSA incorporate a test similar to SAE J1633
or ISO 10454 into its light truck tire standard, using maximum
inflation pressure, limited to tires marked ``LT'' or ``C'' and load
range A-E or Load Index 124 or below. The parameters are as follows:
(1) Speed and duration (ITS = Tire's rated speed -20 km/h): 3-speed
steps: 0 to ITS for 10 min, ITS for 10 min, ITS + 10 km/h for 10 min,
ITS + 20 km/h for 30 min.
(2) Inflation pressure corresponding to maximum load.
(3) Load: 90 percent of maximum.
(4) Ambient temperature: 38 deg.C
+/-3 deg.C.
d. Light Truck Tires--Endurance Test
RMA 2000 concluded that
[a]s with passenger car endurance tests, speed is deemed to be
the greatest determinate of tire failure, followed closely by
inflation pressure * * * In the FMVSS 119 test it wasn't until load
limits became unrealistically high that tires begin to fail.
However, in the four test protocols using combinations of the test
conditions cited above, average hours to failure were more
realistically demonstrated when testing at 120 km/h using the
inflation pressures corresponding to the maximum load rating marked
on the tire (350 kPa for load range C, and 550 kPa for load range
E).
RMA 2000 recommended revising the light truck tire standard to
include the following test parameters:
(1) Inflation pressure: at pressure corresponding to the maximum
load rating marked on the tire.
(2) Speed: constant at 120 Km/h.
(3) Duration and load: Load range A, B, C, & D for 8 hours at 75
percent of maximum rated load, 8 hours at 97 percent of maximum rated
load, and 8 hours at 114 percent of maximum rated load. Load Range E
for 8 hours at 70 percent of maximum rated load, 8 hours at 88 percent
of maximum rated load, and 8 hours at 106 percent of maximum rated
load.
(4) Ambient Temperature: 38 deg.C +/-3 deg.C.
2. Other Substantive Submissions
In February 2001, Michelin presented its suggested Endurance
Certification Test to NHTSA. This is an endurance test for long term
durability, which evaluates the following factors: belt edge stress,
long-term cyclic fatigue and compound evolution. The following table
illustrates the parameters of this test:
----------------------------------------------------------------------------------------------------------------
Metric passenger car Light truck
------------------------------------------------------------------------------
Load range
Standard load Extra load --------------------------------------------
B C D E
----------------------------------------------------------------------------------------------------------------
Test Temperature ( deg.F)........ 100+/-5
100+/-5
[[Page 10059]]
Speed (mph)...................... 60
60
Filling Gas...................... 50%O2/50%N2
50%O2/50%N2
Load (lbs)--% Max Single......... 111 142 112 98 92
Initial Pressure (psi)--Regulated 40 46 57 57 65 80
Regulated........................ ............... ............... .......... ......... ......... .........
----------------------------------------------------------------------------------------------------------------
In May 2001, Michelin supplemented its requested endurance test
with a discussion of the influence of its long term durability
endurance test variables on tire endurance and crack propagation.
Michelin has also recommended replacing the current high speed test
with ISO 10191. ISO 10191 contains test variables substantially similar
to those in SAE J1561 and those recommended by RMA 2000 for the high
speed test for passenger tires.
In a November 2000 submission to the docket, GM provided the
following general comments on the first phase of NHTSA's tire testing
matrix: (1) Increased high speed capability will result directly in
compromises with mass, fuel economy (rolling resistance) and ride
comfort, (2) correlation of laboratory tests with performance of tires
in the field environment is necessary and tires with known acceptable
field performance should serve as reference to acceptable performance
on such laboratory tests, (3) tests that take the tire to failure can
always be developed but may not indicate poor performance and tire
failures on these tests should not be interpreted as an indication of
unacceptable performance, (4) the definition of failure for these tests
should be clarified, and (5) it is recommended that temperature
monitoring be included in the testing.
GM also submitted a number of comments on NHTSA's test matrices.
These comments, specific to NHTSA's preliminary test parameters, are
not discussed in detail here, but are available for review in the
docket.
C. NHTSA Tire Testing at Standards Testing Lab (STL)
Shortly after the enactment of the TREAD Act, the agency initiated
tire testing at Standards Testing Labs (STL) in November 2000 to
evaluate the high-speed performance, endurance performance, and low
inflation pressure performance of a limited number of current
production tires. The agency developed a test matrix which focused on
the five main parameters currently used in tire testing under FMVSS
Nos. 109 and 119: load, inflation pressure, speed, duration, and
ambient temperature. Copies of the test matrix and testing results for
P-metric tires and for LT tires is available in the docket (see the
Tire Test Matrix in NHTSA Docket No. 2000-8011-1).
1. High Speed Testing
The high speed tests included a wide range of values for the test
parameters to facilitate evaluation of the performance of a variety of
tires used on light vehicles. A baseline high speed test was performed
on each of the tire brands using the GTS-2000 high speed test for P-
metric tires and FMVSS No. 109 for the LT tires.\19\
---------------------------------------------------------------------------
\19\ LT tires were not included in GTS-2000 nor are they
required to comply with the high speed test in FMVSS No. 119.
---------------------------------------------------------------------------
The Phase I test matrix included loads of 80, 90, and 100 percent
\20\; inflation pressures of 180 kPa, 210 kPa and 240 kPa; durations at
each speed step of 10 minutes, 20 minutes and 30 minutes; and four
speeds steps beginning at an initial test speed (ITS) 30 km/h below the
rated speed of the tire, and increasing in 10-km/h increments up to the
rated speed (ITS + 30km/h). Some tests were conducted to failure,
beyond the rated speed of the tires, to assess the performance margin
for the tires. In this phase of testing, nine P-metric tire brands and
three LT tire brands were tested using 28 tires per brand, one tire for
each of the 28 high speed tests performed. The total number of tires
tested to the high speed test in this phase was 336 tires.
---------------------------------------------------------------------------
\20\ As stated earlier in this document, load percentages,
unless otherwise specified, are based on the sidewall maximum rated
load.
---------------------------------------------------------------------------
The test results from the Phase I tests show that all but one of
the tires completed the baseline high speed tests up to their rated
speed without failure. The results of the matrix tests indicate that
all the parameters have an impact on tire failure in the high-speed
test; however, a decrease in inflation pressure appeared to have the
greatest impact on time to failure in the high-speed test. For example,
at an inflation pressure of 180 kPa using 20-minute speed intervals,
the results of the P-metric tire tests indicate 3 of 9 tire failures,
while at 240 kPa, under similar test conditions, all 9 tires completed
the high speed test. The data also indicate that RMA 2000's suggested
10-minute test duration at each speed appears to be too short to
properly evaluate the high speed performance of a tire. In the agency's
testing, few failures occurred at the 10-minute steps, and all tires
tested were able to complete many of the tests conducted using 10-
minute speed intervals. In general, the most stringent mix of
parameters was 100 percent load, low inflation pressure of 180 kPa,
combined with the longest test duration for each speed step, 30
minutes. This test condition resulted in only one of nine P-metric
tires completing the high speed test. A similar test condition for the
test on three LT tires resulted in one tire completing the high speed
test. The agency notes that these severe test conditions enabled us to
evaluate the high speed performance limits of some current production
tires.
The agency conducted additional high speed testing using a Phase II
matrix. This second phase of the high-speed testing included 12 tire
brands (8 P-metric and 4 LT tires) with a sample of five tires per test
per brand. The test parameters included loads at 80 and 85 percent;
inflation pressures at 210 kPa and 220 kPa; duration of 20 minutes; and
speeds similar to the ITS plus 10, 20, 30 km/h method used in Phase I,
and also three fixed speeds of 160, 170, and 180 km/h for 30 minutes at
each speed step. For the LT tires tested to the high-speed test, the
parameters were similar as those used for P-metric tires, except that
the inflation pressures were changed to reflect the higher maximum
inflation pressures on those tires.
The test results from the second phase testing demonstrated that
there is variability in the manufacturing quality of tires since a mix
of passes and failures occurred within the 5 samples tested for each
brand.
2. Endurance Testing
The endurance testing was also comprised of two phases of matrix
testing. The baseline endurance test used for the P-metric tires was
the one
[[Page 10060]]
in GTS-2000 for radial tires rated ``Q'' or below. For LT tires, the
FMVSS No. 119 endurance test was used as the baseline. The agency also
conducted endurance testing with load combinations of 100/115/125
percent load, test speeds of 120 and 140 km/h, inflation pressures of
160 kPa and 200 kPa for P-metric tires, and for a duration of 50 hours.
Similar parameters were used for LT tires, except with different
inflation pressures since these tires have higher maximum inflation
pressures than P-metric tires.
All the tires completed the baseline endurance tests without any
failures. The results of the matrix tests for endurance indicate that
the higher test speed, 140 km/h, had a large impact on the time to
failure, even at the higher inflation pressure of 200 kPa. The high
load percentages also contributed significantly to the short time to
failure, especially for some of the LT tires.
The second phase of the endurance testing included test parameters
closer to those that the agency is proposing in this NPRM. The
parameters were as follows: lower loads of 100/110/115 percent combined
with a test speed of 120 km/h at 180 kPa inflation pressure for a
duration of 50 hours; higher loads of 100/115/125 percent combined with
a lower test speed of 100 km/h at 180 kPa inflation pressure for 50
hours.
The results of the second phase of endurance testing indicate that
fewer failures occurred in Phase II testing with the combination of
high load (100/115/125 percent) and lower speed (100 km/h) than under
the parameters of Phase 1 testing. In Phase 2, 7 of the 8 P-metric
tires completed the test without any failures in any of the 5 samples
of each brand tested. The 4 LT tires tested also performed well with
one failure in the five samples in 3 of the 4 brands tested. One brand
completed the test with all 5 tires completing the 50-hour test. The
test conditions that produced the most failures in the P-metric tires
were the higher load combinations at 120 km/h. These conditions,
surprisingly, did not produce many failures in the LT tires tested.
3. Low Inflation Pressure Testing
The agency also conducted a test at low inflation pressures (140
kPa (20 psi) inflation pressure for P-metric tires), at a speed of 120
km/h (75 mph) for a duration of 90 minutes, on the same tires (2
samples of each of the 12 brands) that successfully completed the
endurance test. The purpose of this test was to evaluate tire
performance at a low inflation pressure threshold level, 20 psi, being
proposed for tire pressure monitoring systems for light vehicles.\21\
Similar tests were performed using the LT tires, but at low inflation
pressures values commensurate with 58 percent of their maximum
inflation pressure. These low threshold values were selected based on
the lowest inflation pressure at which a tire load is provided by the
tire industry standardizing bodies. The test results indicate that all
24 tires tested completed the 90 minute test low inflation pressure
test without failure.
---------------------------------------------------------------------------
\21\ In its recent TPMS NPRM, Docket No. NHTSA-2000-8572, the
agency proposed two options for activation of the warning lamp: 1)
20 percent below the recommended cold inflation pressure or 140 kPa
(20 psi) whichever is higher; and 2) 25 percent below the
recommended cold inflation pressure or 140 kPa (20psi), whichever is
higher.
---------------------------------------------------------------------------
4. Conclusions From Testing Results
In summary, the results of the high speed and endurance tests
indicated that the agency can develop and propose test requirements
that are realistic in terms of the test parameters, yet more stringent
than the current FMVSS No. 109, FMVSS No. 119 requirements, European
Regulation ECE R 30, GTS 2000, and RMA 2000. The proposed test
requirements differentiate tires with better high speed and endurance
performance from those with lesser performance. The low pressure
validation tests indicate that tires that were able to successfully
complete the endurance testing can also complete an additional 90-
minute test at a low inflation pressure, 140 kPa for P-metric tires,
thus providing an adequate safeguard for consumers to take corrective
action when the low pressure warning lamp proposed under the tire
pressure monitoring system rulemaking is activated at a
``significantly'' under-inflated level.
VI. Agency Proposal
A. Summary of Proposal
The agency is proposing a single standard for light vehicle tires,
FMVSS No. 139, New Pneumatic Tires for Light Vehicles, which would
require light vehicle tires to meet a high-speed test, an endurance
test, a low inflation pressure performance test, a resistance-to-bead
unseating test, a road hazard impact/strength test, and an accelerated
aging test. This standard would require tires for passenger cars,
multipurpose passenger vehicles, trucks, buses and trailers with a
gross vehicle weight rating (GVWR) of 4,536 kilograms (10,000 pounds)
or less, manufactured on or after November 1, 2003, to comply with the
test requirements. Therefore, this proposal is applicable to LT tires
up to load range E.\22\ The following chart compares the types of test
requirements that currently exist, those that have been suggested by
third parties, and those are being proposed by this agency:
---------------------------------------------------------------------------
\22\ This load range is typically used on large SUVs, vans, and
trucks.
Table 1.--Comparison of Types of Tire Performance Requirements in Various Existing and Draft Tire Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed FMVSS
Tests FMVSS 109 FMVSS 119 GRRF Draft GTR GTS-2000 RMA 2000 ECE R30 139
--------------------------------------------------------------------------------------------------------------------------------------------------------
High Speed....................... X ............... X * X X X X
Endurance........................ X X X * X ** X ............... X
Low pressure performance......... ............... ............... ............... ............... ............... ............... X
Strength; or Road Hazard Impact.. X X ............... ............... ............... ............... X
Bead Unseating................... X ............... X *** ............... ............... ............... X
Accelerated Aging................ ............... ............... ............... ............... ............... ............... X
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Endurance test for radial tires rated ``Q'' and below. Identical testing parameters as FMVSS No. 109 Endurance Test.
** Endurance test for radial tires rated ``Q'' and below.
*** Identical testing parameters as FMVSS No. 109 Bead Unseating Test.
Testing parameters have not been agreed upon by the ad hoc working group.
[[Page 10061]]
Both the proposed High Speed Test and the Endurance test contain
testing parameters (ambient temperature, load, inflation pressure,
speed, and duration) that make the tests more stringent than those
tests currently found in FMVSS Nos. 109 and 119, as well as the tests
suggested by industry. Most significantly, the proposed High Speed test
specifies test speeds (140, 150 and 160 km/h (88, 94, and 100 mph))
substantially higher than those specified in FMVSS No. 109 (120, 128,
136 km/h (75, 80, 85 mph)). Likewise, the proposed Endurance Test
specifies a test speed 50% faster (120 km/h (75 mph)) than that
currently specified in FMVSS 109 (80km/h (50 mph)), as well as a
duration 6 hours longer (40 hours total) than that currently specified
in FMVSS 109 (34 hours total). At the specified test speed (120 km/h),
the Proposed Endurance Test mileage (3,000) is almost double the
mileage that a tire endures under the current Endurance Test (1,700
miles at 80 km/h).
The proposal also contains two alternative Low Inflation Pressure
tests which seek to ensure a minimum level of performance safety in
tires when they are underinflated to 140 kPa. The agency requests
comments on which test is more appropriate to be included in the new
standard.
In place of the current strength test in FMVSS No. 109, the agency
proposes that the new standard contain a Road Hazard Impact test which
is modeled after a SAE recommended practice. This test, which simulates
a tire impacting a road hazard, such a pothole or curb, provides both a
more stringent and more real world test than the FMVSS No. 109
``plunger test.''
The proposal would also replace the current FMVSS No. 109 Bead
Unseating Test with a new Bead Unseating test which is based on a test
currently used by Toyota. Industry has previously recommended to the
agency that the current bead unseating test be deleted from the
standard because radial tires are easily able to satisfy the test.
Results from the agency's 1997-1998 rollover testing, however, provide
a strong rationale for upgrading, rather than deleting, the bead
unseating requirement in FMVSS No. 109. The Toyota test uses test
forces more stringent than those in current FMVSS No. 109 which were
developed for bias ply tires and are typically not stringent enough for
radial tires.
To address the deterioration of tire performance caused by aging,
the proposal contains three alternatives for an Aging Effects Tests.
These tests, the Adhesion (Peel) Test, Michelin's Long-term Durability
Endurance test, and Oven Aging all seek to expose tires to the type of
failures experienced by consumers at 40,000 kilometers or beyond. The
agency requests comments on which test is most appropriate to be
included in the new standard.
The proposal would also revise FMVSS Nos. 110 and 120 to reflect
the applicability of the new standard and would revise certain of the
tests in FMVSS Nos. 117 and 129 to ensure that all light vehicle tires
are required to comply with the identical minimum performance
requirements. Lastly, the proposal discusses NHTSA's ongoing and future
Road Hazard Impact Test and Bead Unseating Test research plans, the
lead time for implementation of the new tire standard, the use of
shearography analysis, and the revision of the requirements for the
test speeds in UTQG Temperature Grading Requirement to mirror those in
the proposed High Speed Test.
NHTSA believes that the proposed upgraded standard would specify
more stringent and real-world, yet practicable, tests that would
provide a higher level of operation safety and performance for tires on
today's light vehicles.
B. Applicability
FMVSS No. 139 would apply to new pneumatic tires for use on motor
vehicles with a GVWR of 10,000 pounds or less, manufactured after 1975,
except for motorcycles. Given the increasing consumer preference for
light truck use for passenger purposes, the agency is proposing that
the safety requirements for passenger car tires also be made applicable
to LT tires (load range C, D, and E) used on light trucks.
Currently, the performance requirements for LT tires in FMVSS No.
119 are less stringent than the requirements for P-metric tires in
FMVSS No. 109. LT tires are required to comply with a strength test and
a low speed endurance test, but are not required to be tested to a high
speed performance test or a resistance-to-bead unseating test as
required under FMVSS No. 109. However, LT tires are increasingly used
in the same type of on-road service as P-metric tires on light
vehicles. Further, recent sales data for heavier light trucks indicate
that the use of these tires on passenger vehicles will continue to
increase in the near future.
NHTSA is not proposing to require that FMVSS No. 139 apply to
motorcycle tires because motorcycle tires are of a design and
construction unlike the types of vehicle tires that would be subject to
the proposed standard (e.g., tread, load carrying capacity) and
motorcycle tires still often use inner tubes. Further, the agency is
not currently aware of any safety problems associated with motorcycle
tires.
NHTSA is also not proposing to require that the new standard be
applicable to tires beyond load range E, which are typically used on
medium (10,001-26,000 lbs. GVWR) and heavy (greater than 26,001 lbs.
GVWR) vehicles, and temporary spare tires,\23\ for two reasons. This
rulemaking is required by the TREAD Act, and must be completed by June
2002. To meet this statutory deadline, the agency has limited its tire
upgrade research and analysis to conventional tires for light vehicles.
The issues associated with upgrading performance standards for tires on
medium and heavy vehicles and temporary spare tires are different from
the issues associated with upgrading performance standards for
conventional tires on light vehicles. For example, medium and heavy
vehicles are equipped with tires that are much larger and have higher
pressure levels than the tires used on light vehicles. Temporary spare
tires are smaller, have higher inflation pressures, and are intended
for shorter distance and lower speed driving than conventional light
vehicle tires. Given the TREAD Act deadline on this rulemaking, the
agency does not have the time to study and analyze sufficiently the
different issues presented by medium and heavy vehicle tires and
temporary spare tires. NHTSA will examine these types of tires after we
have completed this rulemaking.
---------------------------------------------------------------------------
\23\ For the purposes of this notice, a temporary spare tire is
a compact tire intended for temporary use. It is typically labeled
for limited durations and speeds.
---------------------------------------------------------------------------
C. Proposed Test Procedures
1. High Speed Test
NHTSA proposes that the High Speed test be conducted using the
following five parameters:
(1) Ambient Temperature: 40 deg.C (104 deg.F).
(2) Load: 85 percent.
(3) Inflation Pressure: 220 kPa (32 psi) for standard P-metric
tires; 320 kPa (46 psi), 410 kPa (60 psi), 500 kPa (73 psi), for LT
tires load range C, D and E, respectively.
(4) Speed: 140, 150, 160 km/h (88, 94, 100 mph).
(5) Duration: 30 minutes for each speed.
A tire complies with the proposed requirements if, at the end of
the high speed test, there is no visual evidence of tread, sidewall,
ply, cord, inner liner, or bead separation, chunking, broken cords,
cracking, or open splices, and the
[[Page 10062]]
tire pressure is not less than the initial test pressure.
The agency proposes a high speed test with three pre-selected
speeds. This testing methodology is different from that in two
alternatives which were considered by the agency: (1) GTS-2000, and (2)
a high speed test using identical parameters to those proposed above,
except that the test speeds are based on the rated speed of the tire
(initial test speed (ITS), ITS + 10, ITS + 20, ITS + 30) for durations
of 20 minutes at each speed step with a 10-minute warm-up from 0 km/h-
ITS.\24\
---------------------------------------------------------------------------
\24\ Analysis of the results of the NHTSA's high speed testing
at STL indicate that less than 25 percent of the p-metric tires
would have failed the second alternative (3 of 8 p-metric brands had
at least one failure in the five samples tested and for LT tires
there was a 5% failure rate in the 5 tire brands tested).
---------------------------------------------------------------------------
The methodology suggested by the tire industry in GTS-2000 for tire
harmonization and the second alternative determines the test speed
based on the tire's speed symbol rated speed. The following chart
illustrates the rated speed in km/h for each speed symbol.
------------------------------------------------------------------------
Rated speed--
Speed symbol km/h
------------------------------------------------------------------------
F....................................................... 80
G....................................................... 90
J....................................................... 100
K....................................................... 110
L....................................................... 120
M....................................................... 130
N....................................................... 140
P....................................................... 150
Q....................................................... 160
R....................................................... 170
S....................................................... 180
T....................................................... 190
U....................................................... 200
H....................................................... 210
V....................................................... 240
W....................................................... 270
Y....................................................... 300
ZR...................................................... > 300
------------------------------------------------------------------------
The initial test speed (ITS) in GTS-2000 is the rated speed of the
tire minus 40 km/h. The test is conducted at the following speed steps:
ITS, ITS+10 km/h, ITS+20 km/h, ITS+30 km/h and ITS+40 km/h. The final
speed step, ITS+40 km/h, is identical to the rated speed of the tire.
Similarly, the ITS in the second alternative is the rated speed of the
tire minus 30 km/h. The test is conducted at the following speed steps:
ITS, ITS+10 km/h, ITS+20 km/h, and ITS+30 km/h, with the final speed
step being identical to the rate speed of the tire. Therefore, under
both alternatives, each tire with a different speed rating is tested at
different speeds during the high speed test.
Historically, the agency establishes uniform minimum performance
requirements for its safety standards for the item of motor vehicle
equipment. Testing for compliance using the tire's rated speed differs
from that philosophy since it does not establish a single absolute
minimum requirement for all tires, but establishes a relative
requirement based on each tire's maximum design capabilities.
The agency's proposal, based on pre-selected test speeds and
independent of the rated speed of the tire, establishes the same
minimum requirement for all tires, regardless of the designed level of
performance. We believe that such a methodology is equitable for all
tire manufacturers and does not impose higher safety standard
requirements on a tire with a higher level of performance.
The following table illustrates an at-a-glance comparison of the
other standards and suggestions discussed in this document.\25\
---------------------------------------------------------------------------
\25\ FMVSS No. 119 does not currently include a high speed test
for LT tires with a rim diameter above 14.5 inches.
Table 2.--High Speed Test Comparison
--------------------------------------------------------------------------------------------------------------------------------------------------------
Test parameters FMVSS 109 GTS 2000 RMA 2000 ECE 30 Proposed FMVSS 139
--------------------------------------------------------------------------------------------------------------------------------------------------------
Ambient ( deg.C)................... 38.................... 25.................... 38................... 255...... 40
Load (%):
P-metric....................... 88.................... 80.................... 80................... 80................... 85
LT............................. .................... .................... 90................... ...................
Inflation Pressure (kPa):
Standard load P-metric......... 220................... .................... ................... ................... 220
Extra load P-metric............ 260................... .................... ................... ................... 260
LT load range C/D/E............ .................... .................... sidewall max......... ................... 320/410/500
SpeedRating (Std/Extra):
L,M,N.......................... .................... 240/280............... 240/280.............. ...................
P,Q,R,S........................ .................... 260/300............... 260/300.............. 260/300..............
T,U,H.......................... .................... 280/320............... 280/320.............. 280/320..............
V.............................. .................... 300/340............... 300/340.............. 300/340..............
W,Y............................ .................... 320/360............... 320/360.............. 320/360..............
Test speed * (km/h)................ 120, 128, 136......... 0-ITS, ITS, +10, +20, 0-ITS, ITS, +10, +20, ITS, +10, +20, +30... 140, 150, 160
+30. +30 +40.
Duration (mins).................... 90.................... 60.................... 60................... 60................... 90
--------------------------------------------------------------------------------------------------------------------------------------------------------
* For GTS-2000, RMA 2000, and ECE 30, initial test speed (ITS) is defined as the tire's rated speed minus 40 km/h.
An explanation of the proposed parameters is provided below.
a. Ambient Temperature
The proposed ambient temperature is 40 deg.C. This temperature is a
slight increase over the temperature, 38 deg.C, currently specified in
FMVSS No. 109. This temperature reflects the typical daytime
temperatures in the South and Southwestern regions of the U.S. during
the Summer. As discussed earlier, the highest rates of tire problems
occurred in the southern states in the summertime.
b. Load
The load proposed for the high-speed test is 85 percent. The load
percent currently specified in FMVSS No. 109 is 88 percent. As
discussed in greater detail below, decreasing the load from 88 percent
to 85 percent increases the tire reserve needed by a vehicle under
normal loading conditions from 12 percent to 15 percent, resulting in a
larger margin of safety when a vehicle is loaded to its GVWR or its
tires are underinflated.
[[Page 10063]]
Changing the load from 88 percent to 85 percent in the high speed
test would affect the current requirement in S4.2.2 of FMVSS No. 110
which states that the vehicle normal load on the tire is to be no
greater than the applicable load used in the high speed performance
test. ``Tire reserve load'' refers to a tire's remaining load-carrying
capability when the tire is inflated to the vehicle manufacturer's
recommended inflation pressure and the vehicle is loaded to its gross
vehicle weight rating (GVWR).\26\ When a tire is loaded to 88 percent
of the maximum load labeled on the tire sidewall, the unused 12 percent
is considered the reserve load of the tire under normal loading
conditions (curb weight of the vehicle plus three occupants in a
vehicle with a designated seating capacity of five or more.) A change
from 88 percent to 85 percent load on the tire for the high speed test
would, in essence, require a vehicle manufacturer to increase the
reserve load under normal loading from 12 percent to 15 percent. This
requirement may, in turn, necessitate the use of a larger tire size on
some vehicles since the load limit on existing tires may not be
sufficiently high to provide a load reserve of 15 percent of the tire's
maximum rated load.
---------------------------------------------------------------------------
\26\ A reserve load margin is provided by manufacturers to
account for overloading of the vehicle, under-inflation of the
tires, or both.
---------------------------------------------------------------------------
In addition, the requirement for a 12 percent tire reserve under
normal loading conditions currently applies only to passenger cars.
This notice proposes to require light trucks for the first time to have
a specified tire reserve under normal loading conditions. Light trucks
would have to provide the same 15 percent reserve proposed for
passenger cars.
The agency also proposes revised language in FMVSS No. 110 to
clarify that the test load that is compared with the vehicle normal
load must be determined at the vehicle manufacturer's recommended cold
tire inflation pressure, and not at the maximum tire load limit on the
sidewall. The agency believes that since the vehicle normal load
defines loading during normal operation of the vehicle, it is
appropriate to require the load to be determined at the vehicle's
recommended cold tire inflation pressure.\27\
---------------------------------------------------------------------------
\27\ Vehicle normal load on the tire means that load on an
individual tire that is determined by distributing to each axle its
share of the curb weight, accessory weight, and normal occupant
weight and dividing by 2.
---------------------------------------------------------------------------
Although 85 percent loading for the high speed testing of tires
represents a slight decrease from the current 88 percent specification
in FMVSS No. 109, test data from the agency's testing and from RMA
testing indicate that tire failure is more sensitive to speed and
inflation pressure than to loading variations in the 80 to 90 percent
range.\28\ The agency believes that a speed increase from 75, 80 and 85
mph to speeds up to 160 km/h (100 mph) would contribute to a more
stringent test which would more than offset a small decrease in test
load requirements. In Phase I of the agency's testing, 5 of 9 P-metric
tires failed at 90 percent load and 2 of 9 failed at 80 percent. Phase
II of the testing included testing of 8 P-metric tire brands, 5 samples
each, at 80 and 85 percent loads, and with all other test parameters
remaining constant (inflation pressure-220 kPa, 20-minute steps, speeds
ITS to ITS + 30 km/h). In these tests, fewer tire failures occurred at
85 percent load than at 80 percent load.\29\ At 85 percent load, 5 of 8
tire brands had no tire failures in their 5 samples and the other three
brands had at least one failure in the five samples. One brand
experienced failures in all 5 samples tested to the high speed test.
Four brands of LT tires were also tested and all samples for each of
the brands completed the high speed test at 85 percent load without any
failures. This testing appears to confirm that small increases in tire
load have less of an impact on time to failure as compared with changes
in inflation pressure and test speed.
---------------------------------------------------------------------------
\28\ RMA's test data indicate that the time to failure for P235/
75R15 tires decreased by 4 minutes when the load was increased from
80 percent to 90 percent. However, time to failure on the same type
(brand, model, and size) tires decreased by 16 minutes when the
inflation pressure was reduced by 9 psi.
\29\ The agency reviewed the production dates for the tires
tested to the above loads at 80 percent and 85 percent loads to
determine whether the production dates of the tires may have
affected the failure rates. No correlation between production date
and failure at the lower load percentages is concluded because all
of the tires were produced during 2000 and 2001. The agency
concludes that a combination of minor quality differences in the
tires, test procedures, and the relatively small (5 percent) load
change may account for the fewer tire failures at the higher load
factor.
---------------------------------------------------------------------------
c. Inflation Pressure
The agency proposes a test inflation pressure of 220 kPa (32 psi)
for all unrated and speed rated P-metric tires and 260 kPa for extra
load tires. The proposed P-metric tire pressure is the same as that
specified in FMVSS No. 109. The agency proposes the following inflation
pressures for LT tires based upon their higher maximum inflation
pressures: 320 kPa for load range C, 410 kPa for load range D, and 500
kPa for load range E tires. During its testing, the agency incorrectly
used 600 kPa as the maximum load rate inflation pressure for LT tires
with load range ``E'', and calculated test pressures utilizing 600 kPa.
Based on the Tire and Rim Association (T&RA) Yearbook, load range E
tires have an inflation pressure of 550 kPa at its maximum load rating.
Therefore, the test inflation pressures are revised accordingly.
The proposed inflation pressures are based on surveys showing that
tires are typically operated at some level of underinflation.\30\ Given
the tire pressure survey data, the agency selected the proposed test
pressures based on the level of underinflation experienced during
normal vehicle operation. The 220 kPa value represents an under-
inflation of 20 kPa (3 psi) or 8 percent from the 240 kPa maximum
inflation pressure, and 260 kPa represents an under-inflation of 20 kPa
(3 psi) or 7 percent from the 280 kPa maximum inflation pressure.
---------------------------------------------------------------------------
\30\ A tire pressure survey conducted by Viergutz, et al., on
8,900 tires in 1978 reported that almost 80 percent of all tires
were under-inflated with approximately 50 percent under-inflated by
4 psi (28 kPa) or more below the recommended pressure. The average
amount of under-inflation recorded in this survey was approximately
3.2 psi (22kPa) below the recommended amount. More recently, data
from the 2001 NASS Tire Pressure Study, conducted on over 11,000
vehicles, indicate that about 60 percent of P-metric tires used on
passenger cars were under-inflated with about 40 percent being
under-inflated by 3 psi or more below the recommended inflation
pressure. For P-metric tires used on light trucks, about 70 percent
were under-inflated, with about 50 percent under-inflated by 3 psi
or more below the recommended inflation pressure.
---------------------------------------------------------------------------
Although 220 kPa is the same test pressure specified in FMVSS No.
109, this test pressure, in conjunction with the new proposed test
speeds, represents a more stringent test than that contained in FMVSS
No. 109. Agency testing results indicate that 220 kPa is a test
inflation pressure that would be appropriate for the high speed test
given the parameters of speed, load and test duration.
RMA suggested basing the test inflation pressure on the rated speed
of the tire. Tires rated P, Q, R, and S would be tested at 260 kPa;
tires rated T, U, and H are tested at 280 kPa; tires rated V are tested
at 300 kPa; and tires rated W, Y, and Z are tested at 320 kPa.\31\ The
agency believes that these inflation pressure values are too high for
high speed testing because (1) they do not reflect values that are
similar to the cold inflation pressures recommended by vehicle
manufacturers, and (2) they do not correspond well with the real-world
inflation pressures recently obtained
[[Page 10064]]
from the vehicles measured during a recent NHTSA sponsored consumer
tire pressure survey.\32\ Further, the agency has stated in previous
rulemakings that standard load tires with higher maximum inflation
pressures (300 and 350 kPa) are not capable of carrying additional load
at higher inflation pressures beyond 240 kPa. They should be tested at
an inflation pressure similar to that of the 240 kPa maximum inflation
pressure tires. (53 FR 17950, 5/19/88; 53 FR 936, 1/18/88)
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\31\ In some cases, RMA's proposed test inflation pressures are
higher than those labeled on the tire sidewall.
\32\ In Spring 2001, the National Center for Statistics and
Analysis (NCSA) conducted the 2001 National Automotive Sampling
System (NASS) Tire Pressure Special Study (NASS Study) in response
to the TREAD Act. The Preliminary Analysis of Findings, 2001 NASS
Tire Pressure Special Study, dated May 4, 2001, has been placed in
Docket No. NHTSA-00-8572. Data obtained as part of this study
indicate that about 36 percent of passenger cars and 40 percent of
light trucks had at least one tire that was at least 20 percent
below the vehicle manufacturer's recommended cold inflation
pressure. About 26 percent of passenger cars and 29 percent of light
trucks had at least one tire that was least 25 percent below the
vehicle manufacturer's recommended cold inflation pressure.
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d. Speed
The proposed test speeds, 140, 150 and 160 km/h (88, 94, and 100
mph) represent a substantially increased stringency from the test
speeds currently used in FMVSS No. 109 and 119 for which tires are
tested at 75, 80, and 85 mph for 30 minutes at each speed. This
approach would more closely mirror the upper limit of real world
operational speeds beyond which drivers have few opportunities to
operate their vehicles and eliminate from production any tires whose
production just achieved the lowest rung of Temperature resistance
rating in our Uniform Tire Quality Grading System (UTQGS), ``C'' rated
tires.
The agency considered proposing a higher threshold test speed of
180 km/h so that speed rated tires with a speed rating lower than ``S''
(180 km/h) would not have been able to comply with the high speed test.
In the U.S., light vehicles are typically equipped with tires speed
rated no lower than Q (160 km/h). GM suggested that the agency consider
basing our test speed on the speed rating of the tire since many of
their light trucks are equipped with LT tires rated Q and R, 160 km/h
(100 mph) and 170 km/h (106 mph), respectively. NHTSA, however,
believes that an upper test speed threshold of 160 km/h (100 mph)
ensures a minimum level of safe operation that is 25-30 mph beyond
typical speed limits on interstate highways in the U.S.
Under the UTQG test procedure, a tire is rated C if it fails to
complete the test at 100 mph for 30 minutes. The test is initiated at
75 mph for 30 minutes and then successively increased in 5 mph
increments for 30 minutes each until the tire has run at 115 mph for 30
minutes. Therefore, tires with a temperature rating of C would be able
to complete 30 minutes at speeds of 75, 80, 85, 90, and 95 mph (120,
128, 136, 144, and 152 km/h), but not complete the 100-mph (160 km/h)
step. NHTSA, as mentioned above, believes that testing at an upper test
speed threshold of 160 km/h (100 mph) ensures a minimum level of safe
operation.
As discussed above, NHTSA used test speeds based on the speed
rating of the tires for its high speed testing at STL (see the Tire
Test Matrix in Docket No, NHTSA-00-8011-1). While representing a
departure from the methodology of utilizing three predetermined test
speeds (as proposed above and currently used in the FMVSS Nos. 109 and
119 high speed tests), this approach is identical to that contained in
ECE R 30, GTS-2000, RMA 2000, and in SAE Recommended Practice J15161,
Laboratory Speed Test Procedure for Passenger Car Tires. NHTSA seeks
comment on whether test speeds based on speed ratings would be more
appropriate, than those proposed above, for the High Speed Test and,
more specifically, whether the method for determining test speeds
contained in NHTSA's high speed testing matrix or the two alternatives
mentioned above would be appropriate for the High Speed Test in the
final rule.
e. Duration
NHTSA proposes a 30-minute test duration for each of the 3 speed
steps, 140, 150, and 160 km/h. The total test time equals 90 minutes.
The 30-minute duration allows the tire to attain and maintain its
operating temperature at each speed step so that the tire's performance
could be evaluated during a steady rate of speed for a duration longer
than 10 minutes.
Based on its testing, the agency believes that RMA 2000's 10 minute
duration at each speed step (10 minute speed build-up from 0 km/h to
ITS, then five 10 minute speed steps) is too short to provide a proper
evaluation of high-speed performance. Very few failures occurred in the
agency's testing using the 10-minute duration for speed steps.
Additionally, RMA's recommendation reduces the duration currently
specified in FMVSS No. 109 by almost 50 percent.
3. Endurance Test
NHTSA proposes that the Endurance test be conducted using the
following five parameters:
(1) Ambient temperature: 40 deg.C.
(2) Load: 90 percent, 100 percent, 110 percent.
(3) Inflation Pressure--180 kPa (26 psi) for P-metric, 260 kPa (38
psi), 340 kPa (50 psi), and 410 kPa (59 psi), for LT load range C, D
and E, respectively.
(4) Speed--120 km/h (75 mph).
(5) Duration (hrs): 8, 10, 22 (total 40) at the corresponding loads
listed above.
A tire complies with the proposed requirements if, at the end of
the endurance test, there is no visual evidence of tread, sidewall,
ply, cord, inner liner, or bead separation, chunking, broken cords,
cracking, or open splices, and the tire pressure is not less than the
initial test pressure.
This combination of these parameters for P-metric tires represents
a more real-world test and an increase in stringency over FMVSS No.
109's endurance test with an 18 percent increase in the duration, a 10
percent increase in the load, and a 50 percent increase in speed.
Two alternatives to the proposed test parameters were considered by
the agency: (1) RMA 2000, and (2) an endurance test using identical
parameters to those proposed above except for test loads at 100/110/115
percent for durations of 8, 10, 32 (total 50).
RMA 2000 includes no change in the load combination of 85/90/100
percent and a 10-hour (almost 30%) decrease in duration from the
current standard, FMVSS No. 109. The load and duration increase of the
second alternative to a load combination of 100/110/115 and a 16-hour
(almost 50%) increase in duration from FMVSS No. 109 would fail over 40
percent of P-metric tires and 20 percent of LT tires tested.\33\
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\33\ These results, based on NHTSA's endurance testing at STL,
are discussed in more detail below.
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The agency proposes an endurance test that has parameters different
from the two alternatives in load and duration. The agency believes
that, given the change in the composition of the light vehicle market
in the U.S. over the past 10 years towards a greater proportion of
light trucks and vans being used for passenger purposes, the load
values for an endurance tire test should be increased up to 110 percent
to reflect the greater likelihood of vehicle overloading that is more
likely to occur with light trucks and vans than with passenger cars.
Further, the agency believes that an increase in duration for the test
is warranted reflecting the increased life of today's tires. The
increase in duration from 34 hours to 40 hours combined with the
proposed test speed of 120 km/h represents an increase in the total
test distance from
[[Page 10065]]
2720 km (1700 miles) to 4800 km (3000 miles).
The following chart illustrates an ``at-a-glance comparison'' of
the proposed standard to the other standards and suggestions discussed
in this document.\34\
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\34\ For global harmonization, the tire industry recommended an
endurance test for radial tires rated Q and below. The test
parameters included a load of 100/110/115 percent at a speed of 80
km/h. The agency's testing indicates that all the P-metric tires
tested completed the industry's recommended test without any
failures.
Table 3.--Endurance Test
----------------------------------------------------------------------------------------------------------------
New FMVSS
Test parameters FMVSS 109 FMVSS 119 GTS-2000 * RMA 2000 ECE R30 139
----------------------------------------------------------------------------------------------------------------
Ambient ( deg.C)................ 38 38 38 38 N/A 40
Load (%):
P-metric.................... 85/90/100 .......... 100/110/115 80/90/100 N/A 90/100/110
LT-load C/D................. .......... 75/97/114 ............ 75/97/114 N/A 90/100/110
LT-load E................... .......... 66/84/101 ............ 70/88/106 N/A 90/100/110
Inflation Pressure (kPa):
Standard load P-metric...... 180 .......... 180 180 N/A 180
Extra load P-metric......... 220 .......... 220 220 N/A 220
LT-Load C/D................. .......... (**) ............ (**) N/A 260/340
LT-load E................... .......... (**) ............ (**) N/A 410
Speed (km/h).................... 80 80 80 120 N/A 120
Duration (hrs).................. 34 34 34 24 N/A 40
----------------------------------------------------------------------------------------------------------------
* Endurance test recommended for GTS-2000 is only for radial tires rated ``Q'' and below.
** Sidewall max.
The endurance testing conducted in Phase 1 of the agency's testing
was performed at 120 km/h and 140 km/h, with loads of 100 percent, 115
percent, and 125 percent for a total of 50 hours, and at inflation
pressures of 160 kPa and 200 kPa. Many failures occurred at the
combination of low inflation pressure (160 kPa) and high speed (140 km/
h). At a test speed of 120 km/h with an inflation pressure of 200 kPa,
2 of the 9 P-metric tires failed to complete the 50 hour test.
In Phase 2 of the testing, the agency tested with loading
conditions of 100/110/115 percent, (identical to the load recommended
by the tire industry for the endurance test in GTS-2000), 180 kPa
inflation pressure, 120 km/h for 50 hours. For P-metric tires, 2 of the
8 tire brands completed the test without any failures in their 5
samples; the remaining tire brands experienced at least one failure in
the five samples used during the test.
Although neither phase of the endurance testing tested tires at
exactly the same conditions as those proposed above, analysis conducted
by the agency indicates that 19 of the 24 tires tested would pass the
proposed endurance test. This analysis is contained in the PEA. NHTSA
seeks comment on this analysis and whether the two alternatives
mentioned above would be appropriate for the Endurance Test in the
final rule.
A more detailed explanation of the proposed parameters is discussed
below.
a. Ambient Temperature
The proposed ambient temperature is 40 deg.C. This temperature is a
slight increase over the temperature, 38 deg.C, currently specified in
FMVSS No.109, and reflects typical daytime temperatures in the South
and Southwestern regions of the U.S. during the Summer months. As
discussed earlier, the highest rates of tire problems occurred in the
southern states in the summertime.
b. Load
The proposed loads for the endurance test are 90, 100, and 110
percent. These load percentages represent an approximate 10 percent
increase over the load percentages specified for the endurance test in
FMVSS No. 109 (85, 90, and 100 percent) and an increase over those
recommended by RMA 2000.
The load levels originally proposed by the tire industry in GTS-
2000 for P-metric tires rated Q or below were 100/110/115 percent at a
test speed of 80 km/h. Given the increased use of light trucks and vans
by the general public and the larger cargo volumes available in these
vehicles, the agency believes that they are more likely to be operated
in an overloaded condition than passenger cars. Our proposal for loads
in the endurance test, 90/100/110 percent, reflects the need to
increase the loads beyond the loads currently required in FMVSS No. 109
but not to the levels proposed by industry in the original GTS-2000
proposal. The RMA now supports a load combination of 85/90/100 percent
for P-metric tires, which is identical to the test loads currently
required for the endurance test in FMVSS No. 109, but at the higher
speeds of 120 km/h, as proposed by the agency. The load combination
proposed by RMA for LT tires with load C or D is 75/97/114 percent, and
for load range E tires is 70/88/106 percent. The industry's endurance
test proposal for P-metric and LT tires is based on a 24-hour test,
which represents a 10-hour reduction in the endurance test time from
FMVSS No. 109.
c. Inflation Pressure
The inflation pressure of 180 kPa represents a 25 percent under-
inflation for 240 kPa maximum inflation pressure tires and is the same
inflation pressure currently required for the endurance test in FMVSS
No. 109. Tires tested to more severe levels of underinflation, e.g.,
160 kPa, failed much sooner into the 50-hour endurance test than those
tested at 180 kPa.
d. Speed
The proposed test is conducted at 120 km/h (75 mph). The current
endurance test in FMVSS 109 is conducted at 80 km/h (50 mph). A 80 km/h
test speed
[[Page 10066]]
may have been an appropriate test speed in 1968 when initially proposed
for bias ply tires. However, today, it is too low a speed for
evaluating the endurance of today's tires given current vehicle
performance capabilities and speed limits.\35\ In addition, speed
limits on interstate highways across the U.S. have reached as high as
75 mph, with actual vehicle traffic speeds typically at least several
miles per hour above the posted speed limit.
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\35\ According to Automotive News (5/14/01), ``since 1981,
average horsepower has risen 79 percent and vehicle weight has grown
21 percent.'' The power to weight ratio has increased over the past
10 years based on data on selected mid-priced Ford, Chevrolet,
Pontiac, Toyota, and Honda vehicles ranged from about 70 to 90
horsepower (HP) per ton. (Ward's Automotive Yearbooks, 1990 and
2000). In 1995, the federally-mandated 55 mph speed limit was
repealed. Since that time, numerous States have increased speed
limits up to 75 mph.
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e. Duration
NHTSA is proposing a 40-hour test at 120 km/h. The total test
distance is 4800 km (3000 miles), which is almost double the distance
for the current endurance test in FMVSS No. 109 (1700 miles at 80 km/
h). The proposed test duration represents a slight increase from the
current 34-hour te