TRUCK TIRE PAVEMENT CONTACT PRESSURE DISTRIBUTION CHARACTERISTICS FOR THE BIAS GOODYEAR 18-22.5, THE RADIAL MICHELIN 275/80R/24.5, THE RADIAL MICHELIN 255/70R/22.5, AND THE RADIAL GOODYEAR 11R24.5 TIRES. FINAL REPORT

This report presents the results of an experimental investigation into the contact areas and tire contact pressure distributions produced by statically loaded truck tires. For this report, the bias Goodyear 18-22.5 LR-H tire, the radial Michelin 275/80R/24.5 LR-G tire, the radial Michelin 255/70R/22.5 LR-G tire, and the radial Goodyear 11R24.5 LR-G tire were tested. The testing consisted of making contact pressure and contact area prints at the interface between the tire and a steel plate at different wheel loads and tire inflation pressures. The pressure prints were produced using Fuji prescale film. The Fuji prescale film produces color variations, when pressure is applied to it, in such a way that darker pigmentation is produced in zones of higher pressure. The variations in color intensities of the Fuji film prints are related to contact pressure values produced for the film color calibration curve. Then, by digitizing the images and using computer software developed exclusively for this project, the tire contact pressure distributions were determined. The proportions of contact area covered by the various pressure ranges were computed and compared in order to observe the patterns and to estimate the significance of high contact pressures. The contact area prints were made by applying ink to the tire and pressing the tire over a white paper that covered the steel plate. The ink prints have only one color and were used for calculating the tire-plate contact areas. Also, the side tire movements were measured for the tires during testing to allow other researchers to relate subsequent theoretical studies to the experimental results. This report also proposes mathematical models for (1) estimating the tire contact area based on the relative area value (ratio of wheel load over inflation pressure) and (2) estimating the tire vertical stiffness based on the tire contact area.