MEASUREMENT AND ANALYSIS OF TRUCK TIRE PRESSURES IN OREGON

As axle loads have increased, the use of higher tire pressures has become more popular in the truck market. To collect data on tire pressures and types of tires in use, a survey was carried out at a weigh station located near Woodburn, Oregon, on Interstate 5 during the summer of 1986. The data show that 87% of the tires surveyed are of radial construction. The average measured pressures of radial and bias tires are 102 psi and 82 psi, respectively. The survey results show that the difference between the manufacturer's maximum recommended tire pressure and the measured tire pressure is very small, particularly for radial tires. Therefore, if government agencies wish to control tire pressures, it would be expedient to control the manufacturer s maximum recommended pressure rather than the inflation pressure used by truckers. This would ensure reasonable control, since the data collected in this study show that measured and recommended tire pressures are nearly equal. The survey results show that most tires are 11 in. wide with a rim diameter of 24.5 in. (i.e., 11/80 R 24.5 or 11-24.5) and the average tread depth of radial tires is slightly greater than that of bias tires.