Roughness in Steel-Belted Radial Tires-Measurement and Analysis

The roughness performance of sixteen (16) steel-belted radial tires has been studied using high speed uniformity, subjective evaluations, and instrumented vehicle techniques. An analysis of the results indicates that tractive force variation was the principle tire non-uniformity causing roughness in the subject test vehicle, and most probably in a large variety of other 1973 vehicles. This result is due primarily to the fact that the first tractive mode resonance of radial tires (28 Hz) interacts strongly with the principle transfer function resonances for 1973 vehicles (20-40 Hz). This work has also shown that ride jury ratings correlate well with vehicle instrumentation.