Interpretation ID: nht80-4.18

DATE: 11/03/80

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: Uniroyal Inc.

TITLE: FMVSR INTERPRETATION

TEXT: This is in response to your letter of October 10, 1990, requesting clarification of the explanation of Treadwear grading in Figure 2 of the Uniform Tire Quality Grading (UTQG) Standards (49 CFR @ 575.104). You ask whether the explanation can be interpreted to mean that the relative treadwear performance of different tires on the UTQG test course in San Angelo, Texas will be consistent with the relative performance of the tires when driven under comparable conditions on other roads.

In experimental testing leading to promulgation of the UTQG regulation, the National Highway Traffic Safety Administration (NHTSA) tested the treadwear of various tire lines not only on the San Angelo course but on roads in other parts of the country. The agency concluded that the UTQG grades established for different tires in testing on the San Angelo course accurately represent the relative performance of the tires obtainable on roads elsewhere in the United States, assuming that the tires to be compared are run under identical conditions.

The statement in Figure 2 of the UTQG regulation that a tire graded 150 would wear one and one-half times as well on the government course as a tire graded 100 was not intended to suggest that the tire would not wear one and one-half times as well on another course, if conditions of use were controlled. The term "relative performance" in Figure 2 refers to the performance of tires in comparison to other tires, and the term "norm" refers to the consistently obtainable relative performance of tires when tested under controlled conditions. Thus, the explanation indicates that, although the relative performance of different tires will be consistent when the tires are tested under controlled conditions, this relative performance may not be obtainable in actual use, if one tire is subjected to more severe road or weather conditions, abusive driving or improper maintenance.

(Illegible Word) will-provide-confidential treatment for your October 19, (Illegible Word), letter.

Sincerely,

ATTACH.

UNIROYAL, Inc.

October 10, 1980

Joan Claybrook, Administrator -- National Highway Traffic Safety Administration, U. S. Department of Transportation

Dear Ms. Claybrook: We should appreciate NHTSA confirming as promptly as possible our understanding of the following points relating to the official explanation of the treadwear portion of tire quality grading that appears in Figure 2 of the regulation:

1. Please confirm our understanding that it is NHTSA's meaning that the treadwear relationship or ratio between tires that is established on the government test course will continue to exist elsewhere (assuming comparable usage) although the particular mileage obtained elsewhere will be different for the reasons stated in the explanation.

2. Therefore, please also confirm that

(a) the second sentence of the explanation is not to be construed as exclusive in its meaning;

(b) the words "relative performance" in the third sentence are to be construed as referring to the performance of a tire or tires on the test course and elsewhere when compared to themselves and not to other tires; and

(c) the word "norm" in the third sentence is to be construed as referring to the individual performance(s) of a tire or tires on the test course.

We request confidentiality for this letter and your reply because the disclosure of this letter could lead to premature discovery of the commercial plans referred to in our letter of August 14 which NHTSA agreed should be held confidential.

Thank you in anticipation of your attention to our request.

Very truly yours,

G. Montgomery Spindler