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An elastically supported cylindrical shell is used to represent the motion of a pneumatic tire in the plane of the wheel. This is an attempt to utilize shell motion as an analog to the plane motion of the pneumatic tire tread. The idea is suggested by the constructional features of a pneumatic tire, both from the point of view of mass distribution and the distribution of elastic stiffness. The equations of motion for such a model are derived by reference to conventional energy methods. In this derivation, the influence of internal pressure and elastic support of the shell is taken into account. The frequencies are determined as functions of the mode shape, and it is shown that nodes, as well as antinodes, rotate with an angular velocity somewhat less than the angular velocity of the rotating pneumatic tire, to an extent determined by the particular mode shape in question.

Mechanical properties have been obtained from a recent series of truck tire tests using the Highway Safety Research Institute's (HSRI) flat bed tire testing machine. In addition to the vertical and lateral spring rates, a set of three parameters characterizing traction properties of the rolling tire are defined and measured. The influence of tire load and inflation pressure on mechanical properties is found to be significant. Carpet plots of lateral force versus tire operating variables such as camber and slip angle are used to illustrate the effect of changes in ply rating, tread pattern, and wear. Corresponding variations in the mechanical properties are noted. The results of an experiment to determine the relationship between single tire and dual tire force and moment producing capabilities are also described.