Performance of Anti-Lock Braking System Equipped Passenger Vehicles - Part III: Braking as a Function of Tire Inflation Pressure 2002-01-0306

This paper presents the results of original research conducted to evaluate the braking characteristics of passenger vehicles equipped with anti-lock braking systems (ABS) as a function of tire inflation pressure. The conditions studied in this paper are for braking on a dry, level roadway without any steering input. The objective of the paper is to study the effect of tire inflation pressure on the braking systems of common vehicles currently in-use. Comparisons are made between ABS and locked-wheel braking for each vehicle.

The subject of this paper is part of the general topic of passenger vehicle dynamics and stability. Knowledge of how a vehicle performs under a variety of braking conditions is important for a variety of applications such as 1) intelligent vehicle highway systems, 2) vehicle stability and control, 3) vehicle dynamics, and 4) accident reconstruction. To date, a number of studies have been performed to study the locked-wheel braking characteristics of passenger vehicles, but few studies have been published relative to how ABS-equipped vehicles perform as a function of tire inflation pressure while emergency braking. Of interest is a better understanding of how typical passenger vehicles equipped with anti-lock brakes behave as a function of tire inflation pressure.

In our paper we present data obtained utilizing state-of-the-art data-acquisition systems for determination of tire inflation pressure effects on braking for a group of passenger vehicles equipped with ABS. We also present reduced and plotted data for the group of vehicles tested. The results provide an excellent understanding of how a variety of passenger vehicles equipped with anti-lock brakes perform as a function of tire inflation pressure during real-world braking conditions.

We found that ABS braking average deceleration is a minor function of tire inflation pressure. In general, ABS emergency braking is reduced at low and high tire inflation pressures and optimal at or near the tire inflation pressure recommended by the vehicle manufacturer. Some vehicles are more affected by variation in tire inflation pressure than others.

The ABS Index of Performance (the ratio of ABS braking to locked-wheel braking,) ABSIP, varied slightly as a function of vehicle tire inflation pressure. ABSIP varied as little as 1% for one vehicle to as much as about 6% for another as a function of tire inflation pressure.

The locked-wheel braking of one vehicle does not necessarily indicate the locked-wheel braking of another vehicle on the same surface under the same conditions. Likewise, ABS emergency braking of one vehicle does not necessarily indicate ABS emergency braking for another vehicle on the same surface under the same conditions.