A semi-empirical tyre model is described here and used in examining the influences upon tyre forces of changes in: (a) tyre tread depth; and (b) pavement mean texture depth and skid number. Test results show that changes in tread depth lead to changes in cornering stiffness and in the form of the pressure distribution. The ways in which these factors are included in the model and their influences on lateral force characteristics of truck tires are presented and discussed. The influences of tread depth, mean texture depth, and skid number on the sliding friction of truck tires are discussed and equations for representing the frictional characteristics of a worn tyre operating on a wet surface (not flooded to a level well over the tops of the road asperities) are presented in an appendix. The body of the paper concludes with a discussion of future approaches for representing frictional effects.
Abstract