Interpretation ID: 2878o
Technical Secretary for Executive Director
Jamaica Bureau of Standards
6 Winchester Road
Kingston l0
JAMAICA
Dear Mr. Rose:
This responds to your letter, addressed to the Director of the Office of the Federal Register, concerning Federal Motor Vehicle Safety Standard No. l09, New Pneumatic Tires. The National Highway Traffic Safety Administration (NHTSA) is the Federal agency which issued and administers that standard. Your questions are addressed below.
By way of background information, NHTSA issues Federal motor vehicle safety standards under the National Traffic and Motor Vehicle Safety Act, l5 U.S.C. l38l et seq. The term "motor vehicle safety standard" is defined by the Act as "a minimum standard for motor vehicle performance, or motor vehicle equipment performance, which is practicable, which meets the need for motor vehicle safety and which provides objective criteria" (section l02(2)). NHTSA does not grant approvals of motor vehicles or motor vehicle equipment. Instead, section ll4 of the Act requires manufacturers to certify compliance of each motor vehicle and item of equipment with all applicable standards. The Act requires that manufacturers exercise "due care" to ensure that their products conform to each applicable standard (section l08(b)(l)).
I will address your first two questions together. The questions are:
l. In the clause dealing with Test Sample, why are the batch size and sample size not mentioned?
2. Why does the standard make no reference to the frequency of testing.
As indicated above, Standard No. l09 is a minimum performance standard. All tires must be capable of meeting the standard's requirements.
The purpose of the test sample paragraph (S4.2.2.l) in Standard No. l09 is to indicate that a test set for a compliance test consists of three tires. One tire is checked for physical dimensions and is then subjected to resistance to bead unseating and strength, in sequence. The second tire is subjected to the endurance test, and the third tire is subjected to the high speed test.
Paragraph S4.2.2.l is not intended to address the question of how many sets of tires a manufacturer should test as a surveillance procedure during production or what batch size the test sets should be drawn from. A manufacturer is not required to conduct any particular frequency of testing or even to run the actual tests specified by Standard No. l09. Instead, a manufacturer must take whatever steps are necessary to ensure that each of its tires, if tested according to the requirements of the standard, would meet those requirements. (For test purposes, however, any one given tire would only be subjected to one of the three test sequences discussed above.) Since Standard No. l09 includes a number of specific test requirements, it is likely that a manufacturer would find it necessary to do some testing in order to ensure that a tire complied with the standard. For enforcement purposes, NHTSA would test a tire according to the specific test requirements of Standard No. l09.
Your third question is as follows:
3. Why does the standard make no reference to tolerances for tyre concentricity?
NHTSA's standards cover aspects of performance for which the agency has determined there is a safety need. To date, NHTSA has not determined that there is a need for requirements covering tire concentricity tolerances. We note that tire concentricity appears to be primarily an issue of occupant comfort rather than safety.
I hope this information is helpful.
Sincerely,
Erika Z. Jones Chief Counsel
ref:109 d:7/11/88