A Model for Combined Tire Cornering and Braking Forces

The objective was derivation of a tire braking/cornering force model based on only a few standard tests, so that elaborate testing of all possible combinations of lateral and longitudinal forces could be avoided Such a model would be particularly useful for truck and bus tires because testing large tires is expensive and appropriate testing facilities are rare The required model can be derived from the concept of the slip circle (not a friction force circle)

Using the slip circle concept, all tire forces at any cornering/braking combination can be predicted from the results of only two basic tests -- a free-rolling cornering test and straight-line braking test The slip circle concept has been incorporated into a subroutine called the COMBINATOR -- a piece of public domain software sponsored by SAE Cooperative Research

This paper discusses the Slip Circle Model, introduces the COMBINATOR, and demonstrates effectiveness by comparison of modeling results and experimental data