The purpose of a laboratory roadwheel test is to realistically evaluate tires for specific road conditions. To facilitate such tests, ASTM International Committee F09 on Tires has developed a practice to provide an industry standard for commercial radial truck-bus tire laboratory temperature algorithms. The algorithms equilibrate with flat surface (highway) operating temperatures to determine equivalency for road versus laboratory operating conditions.
The result of this identification is a new standard developed by Subcommittee F09.30 on Laboratory (Non-Vehicular) Testing, F2779, Practice for Commercial Radial Truck-Bus Tires to Establish Equivalent Test Severity Between a 1.707-m (67.23-in.) Diameter Roadwheel and a Flat Surface. The standard will be used by government agencies, independent tire testing laboratories and tire manufacturers.
F2779 describes the procedures of using a flat-to-curved surface prediction profiler to identify the equivalent test severity conditions on a 1.707-m diameter laboratory roadwheel from specific flat or highway operating conditions for Load Range F - L tires used on vehicles having a gross vehicle weight rating of greater than 4,536 kg. In addition, the curved-to-flat surface prediction profiler is also described in F2779 for such equivalency use.
“Due to the significance of the tire operating conditions, for example, speed, inflation pressure and load on tire performance, as well as the increased severity of testing on a curved surface, it is necessary to conduct roadwheel tire tests using test conditions that reflect temperature equivalency to specific road (flat surface) operating conditions if a meaningful measure of tire endurance is to be achieved,” says Stanley Lew, manager, industry standards and government regulations, Michelin North America Inc., and an F09 member.
Lew notes that F2779 features the prediction profilers in a special interactive electronic format that can be used to determine laboratory test conditions that provide equivalent tire internal temperatures for the tread centerline, belt edge or ply ending region for the two operational conditions — the curved laboratory roadwheel flat (highway) test surfaces.
The ASTM Research Report RRF9-1002 “Truck-Bus Test Development Task Group Final Report,” dated December 17, 2008, documents the Task Group’s work, data, and results, which were the basis for the F2779 standard.
Technical Information: Stanley Lew, Michelin North America Inc., Greenville, S.C.
ASTM Staff: Rick Lake