Theories on the mechanics of tires and their applications to shimmy analysis

Some theories on tire mechanics and wheel shimmy are discussed and their results compared in an effort to clarify uncertainties as to the validity of the theories. Of particular interest is the comparison of the stretched string and the point contact theories of the mechanics of tires. Contrary to conclusions of some previous investigations, it is found that either of these fundamental, linear theories will predict the shimmy characteristics of wheeled systems if the parameters involved are properly chosen. Nonelastic effects and tire slippage can be and should be included in either theory if further improvement is desired. A simple but important correlation between certain of the parameters of these two basic tire mechanics theories is also demonstrated. The theories are compared with each other and with experimental data.