Effects of Tire Shoulder Wear on Vehicle Rollover Limit Testing

Rollover testing evaluates whether a vehicle will roll over or slide in emergency steering maneuvers. The results may depend upon consistent tire performance through consecutive runs. Researchers in the past have concluded that tire shoulder wear greatly affects the maximum lateral acceleration capability of the tires. This research, however, was performed in the 1970's on bias-ply tires. Tire technology has improved significantly since these results were published. Recent test results on Firestone Wilderness radial tires suggest that as tire shoulder wear increases, the maximum lateral capacity of the tires does not. This paper presents data from thirty J-turn tests performed through the shoulder life of a tire. Results show that maximum tire adhesion levels were independent of run number or tire shoulder wear level. Vehicle dynamics were also consistent throughout the tire's shoulder wear life. Photographs of real-world accident tires of vehicles that were sliding on dry pavement and ultimately rolled over are also presented. These tire shoulder wear patterns are similar to those seen during limit testing.