Laboratory Measurement of Tire Flatspot

Abstract

Abstract Tires flatspot when they remain loaded without rolling for a period of time. The magnitude of this flatspot and the speed with which it recovers due to subsequent rolling are influenced by the temperature and load histories. Experience indicates that controlled measurement in the laboratory is the best way to measure the flatspot characteristics of tires. However, the laboratory test procedure must be based on the flatspot and recovery conditions the tire experiences in the field for the measurements to truly represent tire performance. Processing of the experimental data to compute the initial flatspot and its decay due to rolling also requires special care since the flatspot decays from the first revolution of the tire after flatspot. Effects of flatspot on a tire can be measured in many ways using low or high speed uniformity measurements or by measuring the radial runout of the tire. This paper will address the issues involved in flatspot measurement of tires and also present mechanistic explanation of the influence of test conditions on flatspot.