The Relationship Between Angular Velocity Variations and Fore and Aft Non-uniformity Forces in Tires

In previously published work, fore and aft non-uniformity forces in tires have been attributed to angular accelerations of the wheel and hub assembly. Mathematical models of this kind show that the forces disappear at low speeds, and that there is a resonance associated with the torsional stiffness and moment of inertia of the tire/wheel system. Force measurements at low and high speeds confirm this behaviour.

Because fore and aft forces are very small at low speeds, it has been suggested that low speed measurement of angular velocity variations can provide an indirect indication of the magnitude of high speed non-uniformity forces in tires.

This paper describes the simultaneous measurement of angular velocity and fore and aft forces over a wide speed range and for a large sample of tires, thereby providing a much more stringent test of the model assumptions than force measurements alone. The results fully demonstrate the validity of a simple, single degree of freedom model which describes the essential dependence of fore and aft non-uniformity forces on the dynamic properties and speed of rotation of the tire.