Chapter 4 - Semi-Empirical Tire Models

Abstract

The present chapter treats models that have been specifically designed to represent the tire as a vehicle component in a vehicle simulation environment. The modeling approach is termed ‘semi-empirical’ because the models are based on measured data but may contain structures that find their origin in physical models like those treated in the preceding chapter. The mathematical descriptions are restricted to steady-state situations. The first model that is known as The Similarity Method is based on the observation that the pure slip curves remain approximately similar in shape when the tire runs at conditions (e.g., road friction and wheel load) that differ from the reference condition. The second model referred to as The Magic Formula Tire Model is being treated extensively in this chapter. Car, truck, and motorcycle tire characteristics at many different pure slip and combined slip conditions have been computed with the Magic Formula Model and are presented in comparison with over-the-road tire measurement results. A series of turn slip (also in combined slip conditions) are computed with the Magic Formula Model . Tire ply-steer and conicity are considered and the generation of the overturning moment is modeled.