Interpretation ID: nht75-5.27

DATE: 09/30/75

FROM: AUTHOR UNAVAILABLE; Frank A. Berndt; NHTSA

TO: Bridgestone Tire Co. of America

TITLE: FMVSR INTERPRETATION

TEXT: I am writing to confirm your telephone conversation of June 30, 1975, with Mark Schwimmer of this agency, concerning the treadwear test procedure specified in the Uniform Tire Quality Grading Standards (UTQGS).

As Mr. Schwimmer explained, the UTQGS regulation does not describe the tests which you must perform. It describes the procedures which the National Highway Traffic Safety Administration (NHTSA) will follow in its compliance testing. Your legal duty is to ensure that, when tested by the NHTSA according to these procedures, the tires will meet the grades which you have assigned to them.

In its compliance testing, the NHTSA expects to utilize two teams of drivers operating in two shifts, for the very reasons suggested in your letter of June 19, 1975. As Mr. Schwimmer explained, however, you appear to have misinterpreted the vehicle rotation procedure specified in paragraph (e) (2) (viii) (C) of the regulation, which reads as follows:

Rotate the vehicles in the convoy by moving the last vehicle to the lead position. Do not rotate driver position within the convoy. (emphasis added)

Therefore, the lead drivers ("A" and "E" in your chart) will remain the lead drivers throughout the testing, although the vehicle which they drive will change from day to day. Your chart would be correct if the words "Vehicle No." were replaced by the words "Convoy Position No." and if the vehicles were rotated as follows: Convoy Position No.: 1 2 3 4 Day 1 Vehicle #1 Vehicle #2 Vehicle #3 Vehicle #4 Day 2 Vehicle #4 Vehicle #1 Vehicle #2 Vehicle #3 Day 3 Vehicle #3 Vehicle #4 Vehicle #1 Vehicle #2 Day 4 Vehicle #2 Vehicle #3 Vehicle #4 Vehicle #1 Day 5 Vehicle #1 Vehicle #2 Vehicle #3 Vehicle #4 Day 6 Vehicle #4 Vehicle #1 Vehicle #2 Vehicle #3 Day 7 Vehicle #3 Vehicle #4 Vehicle #1 Vehicle #2 Day 8 Vehicle #2 Vehicle #3 Vehicle #4 Vehicle #1

Sincerely,

BRIDGESTONE TIRE COMPANY OF AMERICA, INC.

June 19, 1975

Office of the Chief Counsel, National Hwy. Traffic Safety Administration

SUBJECT: TIRE WEAR TEST PROCEDURE FOR UNIFORM TIRE QUALITY GRADING STANDARDS

This letter is to check with you if the proposed test procedure shown below, is permissible in view of the (2) (VIII) (C) of "Treadwear grading conditions and procedures" in section 575.104 Uniform Tire Quality Grading Standards, which says:

" (C) Rotate the vehicles in the convoy by moving the last vehicle to the lead position. Do not rotate driver position within the convoy."

1. Proposed Test Procedure

In order that we will be able to run test vehicles 800 miles per day, they are permitted to operate by two (2) shifts and two (2) teams of drivers, one team consists of A, B, C and D drivers and another team consists of E, F, G and H drivers. The following chart may help you to understand the proposed test procedure. Vehicle No. No. 1. No. 2. No. 3. No. 4 Miles 1st shift A B C D 400 1st day 2nd shift E F G H 400 1st shift A B C D 400 2nd day 2nd shift E F G H 400 1st shift A B C D 400 3rd day 2nd shift E F G H 400 1st shift A B C D 400 4th day 2nd shift E F G H 400 1st shift A B C D 400 5th day 2nd shift E F G H 400 1st shift A B C D 400 6th day 2nd shift E F G H 400 1st shift A B C D 400 7th day 2nd shift E F G H 400 1st shift A B C D 400 8th day 2nd shift E F G H 400 Total: 6,400

2. Effect of the proposed test procedure:-

2-1. We will be able to find the results faster.

2-2. San Angelo test course will be made use of effectively by the rubber manufacturers and independent testing companies.

2-3. Safe and accurate driving will be expected by evading continuous and monotonous driving by one driver.

Thank you very much for your kind attention to this matter.

Sota Nakajima Technical Representative