Interpretation ID: aiam2557
Chairman
ASTM Subcommittee F9.10
339 Merriweather Road
Grosse Pointe
Michigan 48236;
Dear Mr. Marick: This responds to your March 2, 1977, letter asking whether the Nationa Highway traffic Safety Administration (NHTSA) still emphasizes or frequently conducts tubeless tire resistance to bead unseating tests as authorized by Standard No. 109, *New Pneumatic Tires*.; As you know, the bead unseating test procedure was adopted from th society of Automotive Engineers Practice J918. It is our understanding that the SAE continues to use this procedure for tire performance tests. The NHTSA is of the opinion that the bead unseating test procedure is a viable laboratory evaluation of the compatibility of a tire and rim combination. This has become especially important since 1975, when the table of approved alternative rims of Appendix A of Standard No. 110, *Tire and Rim Selection*, was deleted, and the tables of standards organizations were adopted. The bead unseating test provides an additional verification of the tire and rim combinations listed in the yearbooks of these organizations.; Standard No. 109 requires several tire performance test: physica dimensions, resistance to bead unseating, strength, endurance, and high speed performance. The NHTSA compliance testing is conducted on a random selection basis. In the case of tires, not every test is conducted on each brand of tire selected for compliance testing, Therefore, the bead unseating test is not always conducted during compliance testing. However, the agency does conduct bead unseating test whenever appropriate and will continue to do so.; Sincerely, Frank Berndt, Acting Chief Counsel