Interpretation ID: aiam1804
President
Truck Trailer Manufacturers Association
2430 Pennsylvania Avenue
N.W.
Washington
DC 20037;
Dear Mr. Calvin: It has come to the attention of the National Highway Traffic Safet Administration that a 'Recommended Practice' issued by the Truck Trailer Manufacturers Association, titled 'Method for Determining GAWR and GVWR for Truck Trailer Certification' may be misleading some trailer manufacturers in their responsibilities to certify their products to Standard No. 121, *Air Brake systems*. The recommended practice was reviewed by the NHTSA in draft form to determine its consistency with Parts 567, *Certification*, and 568, *Multi-stage vehicle manufacture*, of Title 49 of the Code of Federal Regulations.; The NHTSA in a March 30, 1972, letter to Mr. Vincent Grey found th draft consistent with Parts 567 and 568. The draft discusses, among other things, the method for determining the gross axle weight rating (GAWR) of an axle at a speed lower than full highway speed. It appears, however, that some manufacturers have understood the draft's discussion to set out the entirety of their responsibilities under the safety standards, and in particular, Standard No. 121. Although the March 30, 1972, review of the TTMA procedures did approve the use of speed qualifications in establishing GAWR and GVWR on Certification labels, our review only recognized the possibility that in some cases GAWR and GVWR might be properly established on the basis of a speed limitation. (An example of such a possibility would be for a vehicle which was physically incapable of reaching highway speeds.); We do not consider it reasonable to extend that interpretation t permit a manufacturer to establish a reduced- speed rating to avoid a safety standard such as Standard No. 121. A vehicle capable of highway speeds and reasonably expected to be operated at such speeds is subject to Standard No. 121 at weight ratings specified for highway speeds.; In view of the misunderstanding that has arisen, we believe i necessary to clarify our approval letter of March 30, 1972, insofar as it relates to the establishment of GAWR and GVWR. These values, to meet the requirements of SS 567.4(g)(3) and (4), must henceforth be unqualified ratings, and may not be based on reduced speeds. If reduced-speed ratings are to be established, they must be *in addition to* the unqualified ratings, and must appear at the end of the certification label, or on a separate label, and in either case be accompanied by an adequate explanation as to the scope of their use.; We realize that this clarification may force revision of the practice of some of your members. Manufacturers who have utilized this practice should be advised immediately that it is inappropriate under the requirements.; Yours truly, James C. Schultz, Chief Counsel