Interpretation ID: nht74-3.38

DATE: 05/09/74

FROM: AUTHOR UNAVAILABLE; L. R. Schneider; NHTSA

TO: Alfa Romeo, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of April 5, 1974 to Mr. Schneider. You state that you are unable to obtain the ASTM E-249 test tire (4 ply rayon) referenced in the ASTM Method used to determine skid numbers, and you ask whether you may use the ASTM E-501 test tire (belted bias).

Your obligation as a manufacturer is to insure that your certification of compliance is not false and misleading in a material respect, and that you exercise due care in manufacturing to conform to the federal motor vehicle safety standards. A manufacturer is not required to follow specifically the test procedures of the standards, but to ascertain that his product will conform to the standard's requirements when it is tested by these procedures. In determining (Illegible Word) number, therefore, you are not required as a matter of (Illegible Word) to use the ASTM E-249 tire if you can reach the required result with equivalent procedures.

We understand that the original E-501 tire provided a slightly higher reading on dry pavement than the E-249 tire and that it is being redesigned so that the two tires give equivalent readings. We anticipate that, when the tire has been approved by ASTM for use in determining and number pursuant to ASTM Method E-274, we will propose a corresponding amendment to our definition of skid number, presently used in 49 CFR @@ 571.105-75, 571.121, 571.122, and 575.2.