Interpretation ID: nht73-1.16

DATE: 02/27/73

FROM: AUTHOR UNAVAILABLE; Douglas W. Toms; NHTSA

TO: American Automobile Association

TITLE: FMVSS INTERPRETATION

TEXT:

This is in further reply to your letter of January 26, 1973, regarding performance of studded tires and the legal implications of installing studs.

The National Highway Traffic Safety Administration (NHTSA) has not tested studded tires as part of its regular compliance program However, a special test of studded tires outside of the regular compliance program was conducted. The results of this program are presently being prepared for release to the public through NHTSA's Technical Reference Division.

Briefly, in this program, snow tires manufactured and studded by the major tire manufacturers, were tested in accordance with the requirements of Standard No. 109 and to conditions that exceed the requirements of Standard No. 109. Unstudded tires of the same type were tested concurrently for direct comparison.

To summarize the data from this program, both the studded and the unstudded tires passed both the endurance and high speed performance tests, the studded tires without loss of studs. In extension of the high speed test to 1/2 hour at 90 mph and 1/2 hour at 95 mph, some of the studs came out during the 1/2 hour at 95 mph. Some studded tires were run to 103 mph before tread chunking occurred. In extension of the endurance test for three hours with 10 percent increased load each hour, no studs were lost. As a result of this program, it would appear that studded tires do not present special problems when tested to the laboratory wheel tests of Standard No. 109.

We understand that major tire manufacturers in the industry have also run similar tests and determined that studded tires will meet the requirements of Standard No. 109. We recommend that tire and stud manufacturers be contacted directly for additional information concerning studded tire performance.

Under the National Traffic and Motor Vehicle Safety Act, persons who properly install appropriate studs in snow tires designed to be used with studs would not be responsible if the tire failed to conform to Federal standards. Because the installation of studs is clearly contemplated by the tire manufacturers, we would consider the conformity of such a tire to be his responsibility. On the other hand, a person who willfully used improper studs, improper installation procedures or who attempted to stud a tire not designed for studs would be responsible for conformity. Whether proper stud installation was used would depend upon a variety of factors, such as accepted practice, and the tire and stud manufacturers' recommended procedures.

Sincerely,

January 26, 1973

General Benjamin O. Davis -- Assistant Secretary of Transportation for Safety and Consumer Affairs, Department of Transportation

Dear General Davis:

We would like to have all the information now available as to what safety performance compliance testing under MVSS No. 109 and No. 110 for studded tires have been performed by or for the Department of Transportation, and the availability of any related test reports.

Since tire studs may be installed by tire manufacturers' retail outlets as well as independent tire dealers, information is also needed as to the legal implications of modifying a tire by installing tire studs, subsequent to the time it is "DOT" certified by the original tire manufacturer.

Any help you can give would be most appreciated.

Yours sincerely,

John de Lorenzi --

Managing Director,

Public & Government Relations