Effect of Increased Truck Tire Pressure on Asphalt Concrete Pavement

AS axle loads have increased, the use of higher tire pressures has become more popular in the truck market. A survey to collect data on current levels of tire pressure was carried out at a weigh station located on Interstate 5 in Oregon during the summer of 1986. The data show that 87% of the tires surveyed were of radial construction. The average measured tire pressures (hot) of radial and bias tires were 102 and 82 psi (705 and 565 kPa), respectively. This paper presents the results of an investigation into the influence of increased tire pressures on the fatigue and rutting performance and on the vertical compressive stress of asphaltsurfaced pavements. Results of elastic layer analyses (ELSYM5) are presented for two typical Oregon highways to determine levels of stress and strain in the pavements. These parameters are used to develop equivalency factors and to calculate the deformation in the asphalt layer using the results of creep tests. The analyses show that the effect of increased tire pressure on vertical compressive stress is significant in the asphalt surfacing layer. As the pressure increases, the maximum tensile strain at the bottom of the asphalt layer increases. The theoretical equivalency factors take into account tire pressures of 80, 100, 125, and 150 psi (550, 690, 865, and 1,035 kPa) and number of tires per axle (2, 4, and 8 tires). The results indicate that a 25% increase in tire pressure could result in a 40 to 60% increase in equivalency for a dual‐tired single axle of 18,000 lb (80 kN) and a tandem axle of 34,000 lb (150 kN).