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.