Under inflated or deflated tires are known to cause increased forward drag and lateral steering effects on vehicles. This paper documents the results of a series of tests conducted to determine the magnitude and effects of under inflated or deflated tires on cars and light trucks. The first phase of the tests involved the measurement of forward deceleration rates during a series of coast to stop tests with all of the vehicle tires initially inflated to the rated pressure. This was followed by tests at various under inflation pressures. As anticipated all vehicles experienced an increase in the coast to stop deceleration rates at under inflated tire pressure conditions. However, the increase in the deceleration rates were not dramatic in magnitude. The second phase of the tests involved coast to stop tests and lateral motion tests with totally deflated tires in order to simulate a tire blow-out condition. The tests provided consistent results within the test speed ranges up to 45 mph. The results may not be similar at higher speeds and the results should not be randomly extrapolated to higher vehicle speeds without a valid basis. If higher speed affects are desired, the same test methodology is considered to be a reasonable approach to gather data. (A)
Abstract