This paper is an attempt to explain the standing wave phenomena existing in tires at high speeds in terms of tire pressure, tire speed and the tire's stiffness as expressed by its spring constant. The method boils down to reducing the problem to a resonant condition of a simple elastic system.
To reduce the actual tire to an equivalent simple vibrating system, a section equal to the distance between the nodes, or one-half a wave length of the standing wave, is considered as an elastic system between supports. To further simplify, the uniformly distributed weight of this assumed section is replaced by a single equivalent weight from which the natural frequency of the tire section may be calculated. The resonance or standing wave condition occurs when this frequency equals the frequency with which the section of the tire passes the ground contact position.
Simple static experiments were performed to determine the spring constant of the tire (pounds to deflect tire one inch) and the constants used for obtaining the equivalent weights. The final results are represented on a chart where the frequency of the standing wave is plotted against the tire speed for two specific tires of known characteristics. The paper concerns itself with trying to explain standing wave phenomena rather than presenting a lot of data.
