Laboratory tire tests for dynamic spring rate and damping, steady state forces and moments, rolling radius, and cornering force transient measurements are described. Data are shown for bias, belted bias, and radial constructions in a range of automobile tire sizes. The significant differences in the results are noted on all tests for the three tire constructions.
Tire rotation is impeded by a drag force of 10 to 20 lb per 1000‐lb load in normal vehicle operation. The principal cause is hysteresis, which is a function of the viscoelastic properties of the rubber and cord components, the way these materials are used in the tire, and the way the tire is operated. The influence of material properties has been well documented, and many laboratory tests have been developed for their measurement. Of even greater importance to energy losses, however, is tire construction. This subject is developed by consideration of the forces and moments involved in tire operation and of the mechanisms of energy loss. The importance of service conditions is emphasized by a discussion of the factors influencing rolling resistance. Tire rolling losses can be an important fraction of the total power consumption in low‐powered vehicles. Future trends in tire engineering, and their effects on rolling resistance, are discussed.