Interpretation ID: aiam2326
President
Wisconsin Trailer Company
Inc.
Manufacturers Machinery Hauling Trailers
Richfield
WI 53076;
Dear Mr. Mueller: This responds to your June 2, 1976, request for written notificatio that the 'heavy hauler trailer' exclusion of Standard No. 121, *Air Brake Systems*, has been extended to September 1, 1977. You also request confirmation that manufacturers may assign multiple gross vehicle weight ratings (GVWR) and gross axle weight ratings (GAWR) in fulfilling their responsibilities under Part 567, *Certification* (49 CFR Part 567) of our regulations, but that only ratings unqualified by speed restrictions will be permitted after September or October 1976.; I have enclosed a copy of the amendment that extends the 'heavy hauler exclusion of Standard No. 121 from September 1, 1976, to September 1, 1977. The date change in that amendment has been circled.; The NHTSA requires that the GVWR and GAWR placed on the certificatio plate in accordance with Part 567 be unqualified by speed restriction and be based on the 60- mph capabilities assigned to the tire and rims by the United States Tire and Rim Association. Other GVWR and GAWR values may be assigned by the manufacturer, but they must be listed after the information required on the Part 567 certification plate, and they do not form the basis of a vehicle's compliance with safety standards such as Standard No. 121.; In our November 20, 1975, letter to you on the same subject, we note that we were considering a revision of the definition of GVWR and GAWR to conform to this interpretation. That proposal has been issued and a copy is enclosed for your information.; The proposal has not been made final as of the date of this letter Please note that multiple ratings would continue to be permitted under the proposal, so long as the restricted rating appears first on the certification plate.; Yours truly, Stephen P. Wood, Assistant Chief Counsel