A Mathematical Model for a Tire Sidewall

Abstract

Abstract A number of previous experimental studies on the cord load distribution in loaded and inflated bias-ply tires have revealed greatly different cord load fluctuation patterns between the crown and the side-wall regions of the tire. Typical among these is data taken from reference, where the cord load fluctuation measured at the crown center line of a typical bias-ply tire is as shown in Figure 1. The symmetry of this figure is easily explained by either bending or shell membrane considerations or by some combination of these. On the other hand, cord load fluctuations measured in the side wall of a bias-ply tire typically show fluctuations such as shown in Figures 2 or 3, also taken from the previously cited reference. Both of these latter figures show considerable asymmetry of the cord load as a function of position diagrams as the loaded tire is rolled through the contact patch. Bending of the side wall cannot account for such behavior as shown in Figures 2 or 3, since the changes in radius of curvature in the side wall region are completely symmetric about the center line through the contact patch, denoted by the zero degree point in Figures 2 and 3. Simple pressure vessel considerations are also not capable of explaining such diagrams, since changes in curvature in the side wall region are also completely symmetric and hence would result in symmetric stress distributions.