Flat versus Curved Contact Surfaces Effect on Consumer P-Metric and LT Tire Operating Temperatures

Abstract

Abstract Rolling stress and resultant operating temperature is critical to the endurance of a tire. There are fundamental differences between the tire stresses when operating on a flat surface, as experienced in normal highway use, and on a cylindrical laboratory test wheel. Even though there are substantially higher tire stresses and temperatures on a curved test wheel, nonetheless, cylindrical road wheels are widely used with the industry for tire endurance testing. Therefore, it is important to consider the severity of test conditions intended for a flat surface and the equivalent severity on the curved surface in order to avoid subjecting the tire to unrealistic stresses and temperatures. In this study, temperature measurements were made at the tire belt edge and centerline, for both flat and curved surfaces, under designed ranges of load, pressure, and speed conditions. Statistical regression models that predict the temperatures at the tire centerline and belt edge locations are developed and discussed. A simple yet consistent conversion from flat to curved conditions is provided so that equivalent tire temperatures are obtained. Flat highway conditions are derived that are temperature equivalent solutions to each of the FMVSS139 step test conditions.