Tyre Characteristics as Applicable to Vehicle Stability Problems

Abstract

The authors define the characteristics of a pneumatic tyre which affect the handling, or stability, of a car, and briefly describe a machine which was developed to measure these characteristics. The results are given of various experiments showing the effect of several factors on the characteristics; the applicability of these results to the behaviour of a tyre on the road is also discussed. Briefly defining oversteer and understeer, the authors outline a proposed method for directly determining the handling performance of a car while it is still in the drawing board stage. It is pointed out that this will only apply to steady conditions and some of the factors affecting transient behaviour are discussed. In particular, the importance of the self-aligning torque is stressed. The problem of breakaway is mentioned and doubts are cast on the applicability of the machine results to high-speed cornering, or racing; the technique of drifting a car round a corner is discussed. The MS. of this paper was received at the Institution on 17th November 1953, and in its revised form on 11th January 1954. For the report of the meeting in London, at which this paper was presented, see p. 134.