The effects of tire pressure on flexible pavement response and performance were evaluated using data from the first phase of research at the fhwa pavement testing facility. The accelerated loading facility testing machine was used to simulate traffic loading. The response evaluation included measuring surface deflections, surface strains, and strains at the bottom of the asphalt layer for various combinations of load and tire pressure. The data showed little effect due to tire pressure at all load levels. The performance evaluation included an evaluation of differences in rutting and cracking for two test sections trafficked with the same load but different tire pressures. The data showed increased rutting and cracking for the sectiontrafficked with the higher tire pressure; however, this section wasthinner and trafficked at a higher temperature than the low tire pressure section. Based on postmortem evaluations of the two sections and an analysis of pavement strains using layer theory, the increased rutting was due mainly to the higher temperature. On the basis of classical fatigue models, the increased cracking was found to resultprimarily from the combined effects of higher pavement temperature and thinner pavement structure. This paper appears in transportationresearch record no. 1227, Rigid and flexible pavement design and analysis: unbound granular materials, tire pressures, backcalculation, and design methods.
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