Snow Traction Performance of Low Rolling Resistance Drive Tires for Class-8 Tractor Trailers 2012-01-1918

Dynamic traction testing of a sample of drive tires for class 8 tractor-trailers provides information about the relation among rolling resistance, tire design, and traction performance in snow conditions. The tests were conducted to address concerns that low rolling resistance tires used to save fuel and reduce emissions may have inferior traction on snow. In addition to the dynamic traction testing, based on ASTM F-1805, rolling resistance was tested using ISO 28580, and characteristics of the tread design were measured, including tread depth and void ratio, using ASTM F421 and ASTM F-870. In general, tires designed for increased traction, usually made with open shoulders, had a higher snow traction rating than tires designed for highway applications with closed shoulders. There was no significant correlation between the snow traction rating and the coefficient of rolling resistance. Although the tires with the lowest values of rolling resistance tended to have lower snow traction ratings, many tire models with much higher values of rolling resistance had similar low snow traction ratings.

Of the tire design parameters examined, the only one to have significant correlation with the snow traction rating (p≺0.05) was gross contact area, which was not significantly correlated with the rolling resistance coefficient. Conversely, the rolling resistance coefficient was correlated significantly (p≺0.05) only with average tread depth, which was not significantly correlated with the snow traction rating. The results of this investigation suggest that tire manufacturers use a variety of design features in the development of low rolling resistance tires, and that it is possible to design low rolling resistance tires with superior snow traction.