Interpretation ID: nht92-3.17

DATE: 10/15/92

FROM: KENNETH W. WEBSTER II -- PROJECT ENGINEER, TRANSPORTATION RESEARCH CENTER, INC.

TO: MR. PAUL JACKSON RICE -- OFFICE OF CHIEF COUNCIL, NHTSA

ATTACHMT: ATTACHED TO LETTER DATED 12-7-92 FROM PAUL J. RICE TO KENNETH W. WEBSTER, II (A40; STD. 110)

TEXT: This correspondence is a request for clarification of CFR Title 49, Part 571.110, Paragraph 4.4.1(b) (FMVSS 110, "Tire Selection and Rims"). The Transportation Research Center Inc. (TRC) has performed FMVSS certification tests on a passenger car that is to be sold in the U.S. with more than one tire and rim configuration available. Tire retention tests were performed in accordance to NHTSA Test Procedure TP-110-02 at the left front and right rear wheel positions. Since more than one tire and rim configuration is available for the vehicle tested, each configuration was tested at the left front and right rear wheel positions. To save costs, it was desirable to switch only the tire and rim configurations at the test wheel positions while in some cases a different manufactured tire was left on the vehicle at the other wheel positions. In all tire and rim configurations tested, the tires and rims were alike in size, material, traction and type at each wheel position with the exception of a few cases which the tire manufacturer differed.

I cannot locate any information in the CFR 49, Part 571.110 or the NHTSA Laboratory Test Procedure TP-110-02 that indicates all tire and rim configurations are to be exactly alike during the tire retention tests. I have discussed the issue with Zack Fraser who is responsible for FMVSS 110.

Is this a test condition within the requirements of the standard?

Please provide TRC in writing, regarding the Chief Council's position. If you have any questions or require further information before you can determine a position, please contact the undersigned at (513) 666-2011. We thank you in advance for your expeditious reply.