TRUCK NOISE--I. PEAK A-WEIGHTED SOUND LEVELS DUE TO TRUCK TIRES

Abstract

This report is the second in a series of reports to be published as a result of Department of Transportation sponsored truck tire research conducted by the National Bureau of Standards. In conjunction with the first report (OST-ONA-71-9) which contains details of the test design, test procedures, and all data acquired during the first period of testing, this report presents an inventory of peak A-weighted sound levels generated by typical rib, cross-bar and type truck tires. A test sample of nine tread designs, estimated to represent 70-80% (based on discussions with fleetowners) of the truck tire population on the road today, was investigated considering the following variables: wear, loading, speed, pavement surface, and tire location. Test vehicles included both single-chassis vehicles and tractor-trailers. The results show that the A-weighted sound level increased with either an increase in load or speed. The pocket retread design always produced the highest level followed by the cross-bar tires and then the rib tires. This ranking held for tires in all states of wear. The influence of wear and pavement surface, however, is more complex. In general there was an increase in noise level between the new and half-worn states and a slight decrease between the half-worn and fully-worn states. The influence of pavement surface on the generated noise depends on the specific tread design, tire wear condition and the surface roughness. Tires do contribute differently to the overall noise level depending on their location on the vehicle. The data for tractor-trailer tests, for instance, would strongly indicate that the major contribution is made by the tires mounted on the drive axles of the tractor and that the relative contribution of tires mounted on either the front or rear trailer axles depends on the specific tire type and speed of the vehicle.