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NHTSA Interpretation File Search


NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies. 

Understanding NHTSA’s Online Interpretation Files

NHTSA makes its letters of interpretation available to the public on this webpage. 

An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.

  • Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
  • Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
  • The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
  • Some combination of the above, or other, factors.

Searching NHTSA’s Online Interpretation Files

Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.

Single word search

 Example: car
 Result: Any document containing that word.

Multiple word search

 Example: car seat requirements
 Result: Any document containing any of these words.

Connector word search

 Example: car AND seat AND requirements
 Result: Any document containing all of these words.

 Note: Search operators such as AND or OR must be in all capital letters.

Phrase in double quotes

 Example: "headlamp function"
 Result: Any document with that phrase.

Conjunctive search

Example: functionally AND minima
Result: Any document with both of those words.


Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).

Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).


Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”

Complex searches

You can combine search operators to write more targeted searches.

Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”). 

Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”

Search Tool

NHTSA's Interpretation Files Search

Displaying 71 - 80 of 16501
Interpretations Date

ID: 2632y


Mr. Herr T. Spingler
Abt. K2/ELE2
Robert Bosch GmbH

FAX 07121/35-1792

Dear Herr Spingler:

This is in reply to your FAX of July l9, l990, to Richard Van Iderstine of this agency asking for confirmation of an oral interpretation provided you by Jere Medlin, Office of Rulemaking, with respect to replaceable bulb headlamps.

Motor Vehicle Safety Standard No. l08, Lamps, Reflective Devices, and Associated Equipment, defines (section S3) a replaceable bulb headlamp as "a headlamp comprising a bonded lens and reflector assembly and one or two standardized replaceable light sources." In Europe you fix the lens to the reflector assembly with a rubber seal and clips. For the U.S. market you propose to add "silicone-glue at four places between lens and housing to prevent removal of the lens." Mr. Medlin informed you that this would be a "bonded lens and reflector assembly."

The standard does not define "bonded", but the intent of the definition is that, once the lens is joined to the reflector assembly, it shall not be separable. Any method of adhesion that accomplishes this would be a sufficient bond for purposes of the definition. If the application of silicone glue at four places between the lens and the reflector assembly is sufficient to prevent manual separation of the lens from the assembly, then it would be a sufficient bond.

I hope that this answers your question.


Paul Jackson Rice Chief Counsel ref:l08 d:8/2/90


ID: 2633o


Mr. Robert B. Dix, Jr.
Fleet Manager
JKJ Chevrolet
Koons Plaza
2000 Chain Bridge Road
Vienna, VA 22180

Dear Mr. Dix:

This responds to your letter requesting information concerning "after market upfittings". You indicate that you intend to bid on Federal, State or County motor vehicle solicitations and it appears that a number of these solicitations contain specifications that would require "after market upfittings". You asked how our regulations would affect those "after market upfittings".

As you may know, the National Traffic and Motor Vehicle Safety Act of 1966 (15 U.S.C. 1381 et seq.) prohibits the sale or introduction into interstate commerce of any new vehicle or item of motor vehicle equipment that does not conform to all applicable Federal motor vehicle safety standards. The Safety Act authorizes NHTSA to issue these safety standards. NHTSA does not have authority to approve, endorse, or offer assurances of compliance to a manufacturer's motor vehicles or motor vehicle equipment. Rather, the Safety Act established a "self-certification" process, in which each manufacturer is responsible for certifying that its products meet all applicable safety standards.

It is not clear from your letter whether "after market upfittings" means that you will be altering motor vehicles while they are still new, i.e., before they have been sold to a consumer for the first time or that you will be making modifications to used vehicles, i.e., ones that have been purchased already. The requirements applicable to the "after market upfittings" vary, depending on whether the alteration is performed before or after the vehicle has been sold to a consumer for the first time.

I will discuss first the requirements that would apply if you modify vehicles that are new. As modified, the vehicles must continue to comply with all applicable standards, since section 108(a)(1)(A) of the Safety Act prohibits the sale of any vehicle that does not comply with all applicable Federal motor vehicle safety standards. Further, the agency's certification requirements in Part 567 of the Code of Federal Regulations applies to any person who changes previously certified vehicles by means other than the addition, substitution, or removal of readily attachable components or minor finishing operations, or in such a manner that the weight ratings assigned to the vehicle are no longer valid. Such a person is considered an "alterer" for purposes of Part 567 (copy enclosed). The person performing the modifications set forth in your letter (installing a bench seat or adding auxiliary springs) would be considered an alterer, because seats and springs are not readily attachable components.

In this situation, 49 CFR 567.7 requires that:

(1) The alterer supplement the existing manufacturer certification label by affixing an additional label stating that the vehicle as altered conforms to all applicable Federal motor vehicle safety standards as well as stating the firm or individual name of the alterer and the month and the year in which the alterations were completed (see /567.7(a)); (2) The modified values for the vehicle be provided as specified in //567.4(g)(3) and (5), if the gross vehicle weight ratings or any of the gross axle weight ratings of the vehicle as altered are different from those shown on the original certification label (see /567.7(b)); and (3) The type classification be provided, if the vehicle as altered has a different type of classification from that shown on the original certification.

In addition to these certification requirements, an alterer is considered a "manufacturer" for the purposes of notification and recall for defects or noncompliance under the Safety Act and is subject to the requirements of 49 CFR Part 573, Defect and Noncompliance Reports.

With respect to your first point, i.e., that you believe you should "(o)btain from the company doing the work a certification that the after market upfitting meets National Highway Safety Standards," the alterer is required to certify that the altered new vehicle complies with all applicable Federal safety standards.

I am not sure that I understand your second point, i.e., that if a bench seat is installed in a cargo van, the van must have a side door that can be opened from the inside. If you are speaking of an obligation to make some modification to an existing side door, the door would be governed by Standard No. 206, Door locks and door retention system (See 49 CFR 571.206). S4 of Standard 206 provides that the standard's requirements apply to "any side door leading directly into a compartment that contains one or more seating accommodations" and specifies different strength and lock requirements for different types of doors. The addition of a bench seat to what was formerly the cargo compartment would convert that compartment into one subject to S4. The safety standard does not require that the inside rear door handles be operative.

If your second point refers to an obligation to install a side door because you install a bench seat, that is not correct. The Federal motor vehicle safety standards do not impose an obligation that there be a side door in a van. With all of the preceding statements, however, you should note that section 108(c) of the Safety Act provides that compliance with our standards does not exempt any person from any liability under common law. Accordingly, you may wish to consult with a private attorney regarding any product liability concerns you may have about the operability of the door.

Your third point is that you believe that you must place "a decal, label, or some form of paperwork in the vehicle indicating the results of the upfitting." If the "after market upfittings" to which you refer are made to a new vehicle, /567.7 requires the alterer to permanently affix to the vehicle a label setting forth the information specified in that section.

Having discussed the requirements applicable to new vehicles, I now turn to discussing those applicable to used vehicles. If the "after market upfittings" are modifications to used vehicles (in this case, vehicles sold and delivered to a public authority), section 108(a)(2)(A) of the Safety Act applies. This section prohibits any manufacturer, distributor, dealer or motor vehicle repair business from knowingly rendering inoperative any equipment or element of design installed on a vehicle in compliance with our standards. Thus, neither your dealership nor any company that is a repair business or manufacturer can alter legally any vehicle that complies with all applicable Federal motor vehicle safety standards when you receive it (as certified on the motor vehicle by the original manufacturer), in such a way that the vehicle no longer complies with the applicable safety standards.

If the vehicles in question are used vehicles at the time of their modification, the company performing the modifications is not required to provide a separate certification, as discussed in your points 1 and 3. Since you, as the dealer, may be held responsible under section 108(a)(2)(A) for any rendering inoperative by a company acting as your agent, you may wish to get written assurances from the modifier that it has made the modifications in a manner which will not take the vehicle out of compliance with the Federal motor vehicle safety standards. However, that matter is left for your dealership and the modifier to resolve.

As an aid to helping you determine which standards may apply to the modified vehicles, I am enclosing a publication entitled "Federal Vehicle Safety Standards and Procedures." This pamphlet indicates which standards apply to which vehicle types. I also have enclosed a general information sheet for new manufacturers that gives a general description of the applicable regulations, and explains how to get copies of those regulations. I hope this information proves helpful. Please contact this agency again if we can be of further assistance.


Erika Z. Jones Chief Counsel

Enclosures ref:VSA:567 d:12/29/87


ID: 2633y


Mr. Roman L. Cepeda
P.O. Box 3571
Agana, Guam 96910

Dear Mr. Cepeda:

This is in reply to your letter of July 24, l990, to Frank Berndt, the former Chief Counsel of this agency. You wish to import 8 to 12 stainless steel parts. After importation, the parts would be put together to form a Jeep body. Ultimately, an engine, chassis, and all other parts, which are from Guam, would be added to form a completed motor vehicle.

You have asked for confirmation that "the stainless steel jeep body is not a motor vehicle and is not required to meet any provision of the U.S. 49 CFR Part 400 to 999." Apparently, you are having a misunderstanding with Guam Customs on this point.

We are pleased to provide confirmation of your interpretation. There are no Federal motor vehicle safety standards that apply to the stainless steel body parts that you describe. This means that you may import them, as individual body parts, into Guam without violating the National Traffic and Motor Vehicle Safety Act. Under 49 CFR 591.5(i)(2), the appropriate declaration for entry is that they were manufactured on a date when no Federal motor vehicle safety standards were in effect that applied to them.


Paul Jackson Rice Chief Counsel ref:59l d:8/29/90


ID: 2634o


Lawrence C. Bourbeau, Jr., Esq.
Assistant General Counsel
Fruehauf Corporation, Law Department
10900 Harper Avenue
P.O. Box 238
Detroit, MI 48232

Dear Mr. Bourbeau:

This letter responds to your earlier inquiry where you ask whether NHTSA would object to your Company's changing "its model year designation from September 1 to July 1." I apoligize for the delay in responding.

Standard 115, Vehicle Identification Number- Basic Requirements, directs vehicle manufacturers to place a discrete identifying number (VIN) on each vehicle. Title 49 CFR Part 565, VIN- Content Requirements, states that a VIN must include a character indicating the manufacturer's designated model year. Neither Standard 115 nor Part 565 prohibits your company from changing the model year in the manner you suggest. Therefore, such a change does not violate our regulations.

We note that this change apparently concerns model year as a marketing concept. The Federal Trade Commission has published guidelines concerning model year as a commercial concept, and you may wish to contact the Commission for whatever assistance it may provide. I hope you find this information helpful.


Erika Z. Jones Chief Counsel

ref:115 d:12/22/87


ID: 2634y


Mr. Reese Chappell
Auto Ventshade Company
3571 Broad Street
Chamblee, Georgia 30341

Dear Mr. Chappell:

Thank you for your letter asking how Federal regulations would apply to a product called a "Ventvisor" manufactured by your company. You enclosed a brochure that included pictures of the Ventvisor. Described as a rain deflector, the Ventvisor appears to be a strip of molded tinted glazing material several inches wide that is secured on the window frame and running from the front around the top of side windows on motor vehicles. I am pleased to have this opportunity to explain how the requirements of this agency apply to this product.

Some background information about the agency may be useful. NHTSA has the authority under the National Traffic and Motor Vehicle Safety Act to issue safety standards applicable to new motor vehicles and new items of motor vehicle equipment. NHTSA, however, does not approve motor vehicles or motor vehicle equipment, nor do we endorse any commercial products. Instead, the Act establishes a "self-certification" process under which each manufacturer is responsible for certifying that its products meet our safety standards. The agency periodically tests vehicles and equipment items for compliance with the standards, and also investigates other alleged safety-related defects. I have enclosed an information sheet that briefly describes manufacturers' responsibilities under the Safety Act and how to obtain copies of this agency's standards and regulations.

Your company's product is described as made of "acrylic" and would appear to overlap a portion of the side windows of motor vehicles that are "requisite for driving visibility." Accordingly, this product would be a glazing material for use in motor vehicles and would be subject to the requirements of Standard No. 205, Glazing Materials (49 CFR 571.205). Standard No. 205 specifies performance requirements for various types of glazing and also the locations in vehicles in which each type of glazing may be used. The standard also incorporates by reference "ANS Z26," the American National Standards Institute's Safety Code for Safety Glazing Materials for Glazing Motor Vehicles Operating on Land Highways. Standard No. 205 permits devices such as your company's Ventvisor to be manufactured out of either Item 1, Item 2, Item 4, Item 10, or Item 11 glazing materials (the various types of glazing are designated as "Items" in Standard 205). Your company's use of acrylic would appear to be acceptable since this type of rigid plastic could have an Item 4 rating, and Item 4 glazing may be used as a wind deflector on the side window of any vehicle.

You should note that all Item 4 glazing must comply with Test No. 2 in ANS Z26, which requires the material to have a light transmittance of not less than 70 percent. Your letter noted that one version of your Ventvisor is not tinted, while another version is tinted so that it has 47.5 percent light transmittance. This tinted version of the Ventvisor would appear to not comply with the light transmittance requirements of Standard No. 205. The standard also sets forth additional performance requirements for Item 4 glazing, as well as marking requirements for the glazing. If your company determines that the Ventvisor complies with the requirements of Standard No. 205, it may certify each Ventvisor in accordance with the provisions of S6 of Standard No. 205.

Section 108(a)(1)(A) of the Safety Act provides that no person shall "manufacture for sale, sell, offer for sale, or introduce or deliver for introduction in interstate commerce, or import into the United States" any item of new motor vehicle equipment unless the equipment complies with all applicable safety standards and is so certified by its manufacturer. It would be a violation of this section of Federal law for any person to manufacture or sell the Ventvisor or any other glass or plastic wind deflector to be mounted on front side windows, unless those products comply with all requirements of Standard No. 205. Federal law provides for a civil penalty of up to $1,000 for each such violation.

Manufacturers of motor vehicle equipment, such as the Ventvisor, also have responsibilities under the Safety Act for any defects related to motor vehicle safety that are determined to exist in their products. The Safety Act requires such manufacturers to notify purchasers about any defects related to motor vehicle safety and to remedy such defects free of charge.

I hope this information is helpful. If you have any further questions or need any additional information about this topic, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.


Paul Jackson Rice Chief Counsel /ref:205#VSA d:8/2/90


ID: 2635o


Frank S. Perkin, Esq.
Assistant General Counsel
The Budd Company
Law Department
3l55 West Big Beaver Road
Box 260l
Troy, Michigan 48084

Dear Mr. Perkin:

This responds to your letter expressing concern about a statement in one of our interpretation letters, which you believe could be read as condoning the practice of rebuilding wheels by processes which include heating and welding. As discussed below, our letter's reference to remanufacturing wheels was made only to serve as an illustrative example and was not intended to address either the safety of such processes or the relevant regulations of other Federal agencies.

The interpretation letter in question is one that we sent on September 22, l986, to Steven R. Taylor, responding to a request concerning regulations that apply to manufacturers of reconditioned brake drums. The letter included the following paragraph:

NHTSA has in the past considered the issue of what types of operations make a person a manufacturer with respect to retreaded tires and remanufactured wheels. A person who retreads tires is considered to be a manufacturer under the Vehicle Safety Act. The retreading process involves significant manufacturing operations, which do not differ substantially from those of manufacturing new tires. By contrast, a person who remanufactures wheels is not considered to be a manufacturer under the Vehicle Safety Act. The process of remanufacturing wheels consists of such things as straightening, re-welding parts, and repairing cracks by welding. These types of actions are not significant manufacturing operations, but instead are the type of operations commonly performed in repair shops.

You stated that all of the things mentioned in our letter, i.e., straightening, re-welding parts and repairing cracks by welding, are specifically prohibited by the OSHA standard applicable to truck wheels, both multi and single piece. You also stated that the "out of service" criteria adopted by the Bureau of Motor Carrier Safety mandate that a vehicle be placed out of service if welded repairs are found on certain disc wheels. According to your letter, any significant changes made after the manufacture of a steel truck wheel, especially involving bending, heating or welding, carry a significant risk of rendering the wheel unsafe.

As is indicated from the context of our September 22, l986 interpretation letter, the reference to remanufacturing wheels was made solely for the purpose of providing an illustrative example and was not intended to address either the safety of such processes or their permissibility or impermissibility under the relevant regulations of other Federal agencies. I would note that NHTSA has long taken the position that remanufactured wheels are considered to be used wheels instead of new wheels for purposes of Federal motor vehicle safety standards. See, for example, our November 28, l973 letter addressed to Mr. L. Clinton Rich and February 7, l983 letter to Mr. H. J. Lindekugel (copies enclosed). Again, however, these letters do not purport to address the safety of remanufacturing wheels or the relevant regulations of other Federal agencies.

We appreciate your bringing to our attention your concern about the safety of remanufactured wheels. Copies of this correspondence are being placed in the public docket.


Erika Z. Jones Chief Counsel

Enclosures ref:VSA#110#120 d:1/22/88


ID: 2635y


Mr. David J. Blackwell
Operations Manager
Liquidus Limited
37A Shorncliffe Road
Toronto, Ontario
48Z 5K2, Canada

Dear Mr. Blackwell:

This is in response to your letter asking whether a certain vehicle that you plan to export to the United States would be subject to the Federal Motor Vehicle Safety Standards. You state that Liquidus has "designed a system" by customizing an existing road tanker for "overhead" loading. The vehicle you plan to export would be used for "aircraft de-icing storage" and "loading of aircraft de-icing tarmac vehicles while in a fixed location." The road tanker used in your system was originally built in Canada by a firm that has since gone out of business. I am pleased to have this opportunity to explain our statute and regulations to you.

The National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 et seq.; the Safety Act) authorizes this agency to issue safety standards for new "motor vehicles" and new items of "motor vehicle equipment." Accordingly, your vehicle is subject to the safety standards only if it is considered within the definition of "motor vehicle" under the Safety Act. Section 102(3) of the Safety Act (15 U.S.C. 1391(3)) defines a "motor vehicle" as

any vehicle driven or drawn by mechanical power manufactured primarily for use on the public streets, roads, and highways, except any vehicle operated exclusively on a rail or rails.

We have interpreted this language as follows. Vehicles that are equipped with tracks or are otherwise incapable of highway travel are plainly not motor vehicles. Tractors and other agricultural equipment are also not motor vehicles. Further, vehicles designed and sold solely for off-road use (e.g., certain airport runway vehicles and underground mining vehicles) are not considered motor vehicles, even though they may be operationally capable of highway travel. In addition, items of mobile construction equipment which use the highways only to move between job sites and which typically spend extended periods of time at a single job site are not considered motor vehicles.

On the other hand, vehicles that use the public roads on a necessary and recurring basis are motor vehicles. For instance, utility vehicles like the Jeep are plainly motor vehicles, even though they are equipped with special features to permit off-road operation. If a vehicle's greatest use will be off-road, but it will spend a substantial amount of time on-road, NHTSA has treated it as a motor vehicle. Further, if a vehicle is readily usable on the public roads and is in fact used on the public roads by a substantial number of owners, NHTSA has treated the vehicle as a motor vehicle. This finding was made with respect to dune buggies, notwithstanding the manufacturers' statements that the vehicles were not intended to be used on the public roads.

NHTSA has also stated in many prior interpretations that even vehicles that will regularly be used on the public roads will not be considered motor vehicles for the purposes of the Safety Act, if the vehicles have a maximum attainable speed of 20 miles per hour (mph) or less and have an abnormal configuration that readily distinguishes them from other vehicles on the road.

We would apply these principles to the vehicle identified in your letter as follows. Your letter stated that this vehicle will be immobilized after it reaches the airport. Assuming this immobilization occurs, this vehicle would appear to be designed and sold solely for off-road use, just like certain other airport runway vehicles. In this case, it would not be a motor vehicle, even though it is operationally capable of highway travel before the immobilization.

However, if the vehicle were not subsequently immobilized, and were moved from airport to airport with only a limited stay at any job site, this vehicle might be considered a "motor vehicle." This conclusion would be even more likely if a significant percentage of the vehicle's purchasers were to use the vehicle by moving it from airport to airport, notwithstanding your company's intent that the vehicles not be so used. This situation would be analogous to the classification of dune buggies.

I hope that this information is helpful. If you have any additional questions, please contact John Rigby of this office by mail at the above address or by telephone at 202-366-2992.


Paul Jackson Rice Chief Counsel /ref:VSA d:8/20/90


ID: 2636o


The Honorable Harris W. Fawell
House of Representatives
Washington DC 20515

Dear Mr. Fawell:

I have been asked to respond to your recent letter asking the Department of Transportation to provide you with information concerning the use of safety belts on school buses. You ask for this information on behalf of your constituent, Mr. Wayne Mann, in the Illinois Palos Community Consolidated Schools. Mr. Mann specifically seeks "factual information relative to seat (lap) belts on school buses," and information on funding for traffic safety programs involving hazardous conditions outside the school bus.

I would like to begin with some background information on our school bus regulations. The National Highway Traffic Safety Administration (NHTSA) is responsible for developing safety standards applicable to all new motor vehicles, including school buses. In 1977, we issued a set of motor vehicle safety standards regulating various aspects of school bus performance. Among those standards is Standard 222, School Bus Passenger Seating and Crash Protection. Standard 222 requires large school buses (those with a gross vehicle weight rating over 10,000 pounds) to have passenger crash protection through a concept called "compartmentalization."

Compartmentalization requires large school buses to incorporate certain protective elements into the vehicles' interior construction, thereby reducing the risk of injury to school bus passengers without the need for safety belts. These elements include high seats with heavily padded backs and improved seat spacing and performance. (Our regulations require a safety belt for the school bus driver because the driver's position is not compartmentalized. Further, because small school buses experience greater force levels in a crash, passengers on these vehicles need the added safety benefits of the belts.)

School buses continue to have one of the lowest fatality rates for any class of motor vehicle. Large school buses are among the safest motor vehicles because of their size and weight (which generally reduce an occupant's exposure to injury-threatening crash forces); the drivers' training and experience; and the extra care other motorists take when they are near a school bus. For these reasons, NHTSA has not required safety belts in large school buses.

I enclose a copy of a June 1985 NHTSA publication titled "Safety Belts in School Buses," which discusses many of the issues relative to this subject. I think your constituent may find this information helpful.

With respect to hazardous conditions outside the school bus, the agency realizes that there are special problems of driver visibility associated with transporting students. NHTSA has addressed these problems in Federal Motor Vehicle Safety Standard 111, Rearview mirrors, paragraph S9. In 1975, NHTSA established special mirror requirements for school buses "to reduce the danger of death or injury to school children (by giving) the school bus driver the fullest possible view of all sides of the vehicle..." (The proposed rule, including this preamble quotation, appears at 40 FR 33828, 33829, August 12, 1975. The final rule was published originally at 41 FR 36023, August 26, 1976.) One of these special requirements is that manufacturers equip a school bus with a crossview mirror that permits the driver to see the area in front of the bus. These special school bus mirror requirements help contribute to the low number of fatalities associated with school bus travel.

Your constituent also mentions funding to implement a program to address hazardous conditions outside the school bus. The agency believes that its school bus regulations effectively address the safety of school bus design and performance, and contribute to occupant safety.

We note, however, that /402 of the Highway Safety Act, provides funds to each State for its use in conducting a highway safety program. Some of these funds are distributed by the State to local governments or organizations within the State. To get information on Illinois' /402 funds, I suggest that your constituent contact the Illinois Governor's Representative for Highway Safety, Mr. Melvin H. Smith, Director, Division of Traffic Safety, 319 Administration Bldg., 2300 South Dirksen Pkwy., Springfield, IL 62764.

If you or Mr. Mann have further questions, I encourage you to contact our agency.


Erika Z. Jones Chief Counsel Enclosure ref:111#222 d:1/12/88


ID: 2636y


Mr. Jack E. Eanes
Chief, Vehicle Services
State of Delaware
Department of Public Safety
Division of Motor Vehicles
P. O. Box 698
Dover, Delaware, 19903

Dear Mr. Eanes:

This is in response to your letter asking whether very darkly tinted rear windows that obscure the center highmounted stop lamp (CHMSL) required in passenger cars manufactured on or after September 1, 1985 would violate any Federal laws or regulations. Let me begin by apologizing for the delay in this response. I am pleased to have this opportunity to explain our laws and regulations for you.

The National Traffic and Motor Vehicle Safety Act (the Safety Act) authorizes this agency to issue safety standards applicable to new motor vehicles and new items of motor vehicle equipment. We have exercised this authority to issue two safety standards that are relevant to your question. The first of these is Standard No. 108, Lamps, Reflective Devices, and Associated Equipment (49 CFR 571.108), which applies to all new vehicles and new replacement equipment for motor vehicles. Among the requirements set forth in this Standard is a requirement for all passenger cars manufactured on or after September 1, 1985 to be equipped with a CHMSL of specified minimum size, brightness, and visibility from the range of locations set forth in the standard. The second relevant standard is Standard No. 205, Glazing Materials (49 CFR 571.205). This standard applies to all new vehicles and all new glazing for use in motor vehicles, and includes specifications for minimum levels of light transmittance of the glazing (70 percent light transmittance in areas requisite for driving visibility, which includes all windows in passenger cars).

Section 108(a)(1)(A) of the Safety Act (15 U.S.C. 1397(a)(1)(A)) provides that no person may manufacture or sell any vehicle unless it is in conformity with all applicable safety standards. A new passenger car with a rear window tinted so darkly that the CHMSL was not easily visible would probably not be in conformity with Standards No. 108 and 205, and so could not legally be manufactured or sold in the United States. However, this prohibition on the manufacture or sale of a nonconforming vehicle does not apply after a vehicle is first sold to a consumer.

Both before and after the first sale of a vehicle, section 108(a)(2) of the Safety Act (15 U.S.C. 1397(a)(2)) provides that: "No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative, in whole or in part, any device or element of design installed on a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard . . ." If any of the listed commercial entities were to install tint film or otherwise darken the rear windows on passenger cars so that the light transmittance of that window plus the darkening material was below 70 percent, those entities would be "rendering inoperative" the light transmittance of the rear window of the car, in violation of Federal law. This same prohibition in Federal law makes it unlawful for a service station to permanently remove the safety belts or permanently disconnect the brake lines on a car.

Please note that the Safety Act does not apply to the actions of individual vehicle owners. Vehicle owners may alter their own vehicles and operate them on the highways as they please, even if the vehicle no longer complies with the safety standards after such alterations. Hence, no provision of the Safety Act or our safety standards makes it unlawful for vehicle owners themselves to tint or otherwise darken the rear window of their car so that its light transmittance is below 70 percent and/or its CHMSL is obscured.

The individual States, however, do have authority to regulate the modifications that vehicle owners may make to their own vehicles. The States also have the authority to establish requirements for vehicles to be registered or operated in that State.

You indicated in your letter that the State of Delaware "allows vehicle rear windows to be tinted as dark as the owner desires." While I am not familiar with Delaware law, I assume that this statute, and similar statutes adopted by other States, does not purport to legitimize conduct -- the rendering inoperative of glazing and CHMSLs by firms installing window tinting -- that is illegal under Federal law. In other words, any commercial firms installing window tinting that results in light transmittance of less than 70 percent and/or reduces the required brightness of the CHMSL would have violated the "render inoperative" provision in Federal law, even if Delaware permits individual owners to make such modifications themselves and to register and operate vehicles with rear windows and CHMSLs that would not comply with the requirements of the Federal safety standards for new vehicles. Conversely, the Federal law setting requirements for the manufacture and sale of new vehicles and limiting the modifications commercial enterprises can make to those vehicles does not prohibit the State of Delaware from establishing lesser limits on owner modifications to their own vehicles and as the minimum requirements for vehicles to be operated and registered in the State of Delaware.

Thus, there does not appear to be any legal conflict between Federal law and Delaware law, and Delaware would be free to enforce the provisions of its law. We would, however, urge the State of Delaware to carefully consider the adverse safety consequences that will result from the provision of its law. NHTSA has determined that a 70 percent light transmittance minimum for new vehicles is the appropriate level to assure motor vehicle safety, and that the CHMSL on passenger cars enhances motor vehicle safety. It is not clear why the State of Delaware would conclude that the safety need that justifies requiring not less than 70 percent light transmittance and CHMSLs in new passenger cars is satisfied by allowing far lower light transmittance levels and lower-brightness CHMSLs in passenger cars to be operated in the State.

I hope that this information is helpful. If you have any further questions or need additional information about this topic, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.


Paul Jackson Rice Chief Counsel /ref:108#205#VSA d:7/3l/90


ID: 2637o


Mr. E. W. Dahl
Vice President
Goodyear Tire and Rubber Company
Akron, Ohio 443l6-000l

Dear Mr. Dahl:

This responds to your letter concerning the tire marking requirements of Standard No. ll9, New Pneumatic Tires for Vehicles Other Than Passenger Cars. You asked whether the standard would prohibit the following size designations from being marked on the tire:

385/65R22.5 REPLACES l5R22.5

425/65R22.5 REPLACES l6.5R22.5

445/65R22.5 REPLACES l8R22.5

As discussed below, it is our opinion that the above markings are prohibited by Standard No. ll9.

The marking requirements for tires subject to Standard No. 119 are set forth in section S6.5 of the standard. Section S6.5(c) requires that each tire be marked on both sidewalls with "the tire size designation as listed in the documents and publications designated in S5.1."

As noted by your letter, NHTSA recently provided an interpretation letter to Michelin, dated July 9, l987, concerning one of the exact sizes included in your request. The agency stated the following:

In a broader sense, the practice of labeling two tire sizes on one tire, as you requested in your letter, was once a fairly common practice and was referred to as "dual-size markings." Dual-size markings were a marketing effort by tire manufacturers to try to persuade consumers to change the size and/or type of tire on their vehicles, by representing that this particular tire size was an appropriate replacement for two different sizes of tires. However, the practice of using dual-size markings confused many consumers about the size of the tire on their vehicle. The only purpose of the Federally required markings on tires is to provide consumers, in a straightforward manner, with technical information necessary for the safe use and operation of the tire. The agency concluded that it was inappropriate to permit a marketing technique that was confusing many consumers to defeat the purpose of the required markings on tires. Accordingly, dual-size markings were expressly prohibited for passenger car tires subject to Standard No. 109; 36 FR 1195, January 26, 1971.

While Standard No. 119 does not expressly prohibit dual-size markings, section S6.5(c) uses the singular when it refers to the "tire size designation" to be labeled on the tire. Considering the past history associated with dual-size markings, this agency interprets section S6.5(c) of Standard No. 119 as prohibiting a manufacturer from marking a tire with two different size designations, even if a document or publication designated in S5.1 were to show two different size designations for the same tire size.

The tire size marking at issue in the Michelin interpretation differs from your proposed marking in that it did not include the word "replaces." You stated the following:

In the case at hand, the metric size tires are dimensionally equivalent to the sizes being replaced, and have equal or greater load capacity. There is bona fide intent that the replacement sizes will in due course supersede the replaced sizes in terms of production and marketing. We wish to emphasize that the markings in question are not intended as an effort by Goodyear to persuade consumers to change the size and/or type of tires mounted on their vehicles.

As indicated in our letter to Michelin, the only purpose of the Federally required markings on tires is to provide consumers, in a straightforward manner, with technical information necessary for the safe use and operation of the tire. Any practice of using dual-size markings has the potential for confusing consumers about the size of the tire on their vehicle, since consumers may erroneously believe that a particular tire can be considered as meeting fully the criteria of more than one tire size designation. For example, a consumer seeing a tire marking that size A replaces size B might erroneously believe that it is appropriate to replace size A with size B.

You cited a l974 notice of proposed rulemaking (NPRM) for Standard No. l09 which stated that NHTSA believed that the providing of replacement size information on the tire itself was advantageous to consumers. See 39 FR l0l62.

I would note several things about the background and subsequent history of that NPRM. The NPRM indicated that despite the clear language in Standard No. l09 that each tire must be labeled with "one size designation, except that equivalent inch and metric size designations may be used," NHTSA had previously taken the position [in interpretation letters] that replacement markings constituted an exception to this requirement. (Emphasis added.) The interpretation letters had not offered any basis for concluding that this exception existed. (See June 8, l97l letter to Mercedes-Benz; January l9, l972 letter to Kelly-Springfield; March 2, l973 letter to Samperit.)

The NPRM sought to "clarify the labeling requirements of Standard No. l09, to allow, subject to certain conditions, the labeling of replacement tire size designations." However, the NPRM was not adopted as a final rule. We also note that while the l97l-72 interpretation letters cited above do not appear to have been expressly overruled, our February 7, l980 interpretation letter to Michelin (copy enclosed) concluded that Standard No. l09 prohibited replacement markings.

NHTSA has never interpreted Standard No. ll9 to permit any type of dual size markings, including replacement markings. Based on the reasoning presented in our July 9, l987 interpretation letter to Michelin, and the additional discussion presented above, we conclude that Standard No. ll9 prohibits a manufacturer from marking a tire with two different size designations, even if the word "replaces" is used.


Erika Z. Jones Chief Counsel

Enclosure ref:l09#ll9 d:1/7/88


Request an Interpretation

You may email your request to or send your request in hard copy to:

The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590

If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.

Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.