Evaluation of Effects of Tire Size and Inflation Pressure on Tire Contact Stresses and Pavement Response

Recent years have seen an increase in the number of permitted oversized and overweight loads on Texas highways. The motor carrier industry uses a number of tire sizes in transporting oversized and overweight loads. Tire inflation pressures for these transports are often higher than those used for regular line hauling to match the higher wheel loads of the overweight truck or trailer. In evaluating the structural adequacy of pavements to applied wheel loads, existing practice typically assumes the tire pressure to be uniform over the contact area with magnitude equal to the inflation pressure. This analysis ignores the differences in tire footprints among various tire types. To determine the effects of these differences, researchers investigated existing procedures for predicting pavement response to applied surface tractions at the tire-pavement interface. A specific objective was to establish how tire contact stresses may be modeled in existing layered elastic programs to better approximate the effects of non-uniform tire contact pressure distributions, and account for differences in tire construction, tire load, and tire inflation pressure on predicted pavement response. To this end, researchers assembled a data base of measured tire contact stresses and performed a comparative evaluation of methods for representing tire contact pressure distributions in existing models to predict performance-related pavement response variables. A computer program called TireView was developed that provides estimates of tire contact area as a function of tire type, tire load, and tire inflation pressure and predicts the stress distribution at the tire-pavement interface based on polynomial interpolations of measured tire contact stresses in the data base. A method for predicting pavement response using layered elastic analysis is proposed that is based on the predicted tire contact area. Alternatively, the predicted tire contact pressure distribution from TireView may be used in a finite element program for applications where a more rigorous analysis is desired.