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The interaction between tyre and road is a complex non-linear process including radial and tangential contact forces between tyre and road surface. During recent years models have been developed which allow for predicting radial forces as function of surface and tyre properties. These models can be used to quantify the influence of radial forces on the noise generation. Whereas in many cases time varying radial forces are the main reason for the generation of tyre noise, in some cases other mechanisms seem to be dominant. This paper aims on understanding the influence of tangential contact on tyre/road noise generation. For this reason the model developed by the Chalmers Tyre Road Noise Group has been extended to also include tangential interaction. The model is based on the same concept as that used by McIntyre and Woodhouse for modelling string/bow contact of musical instruments. It computes the time varying normal and tangential contact forces for a tyre rolling over a rough surface at constant speed. A small selection of simulation results are presented aiming at showing the effect of different parameters, such as friction coefficient and normal load, on the occurrence of instability phenomena such as stick/slip vibrations.

Tyre/road noise generation mechanisms are divided into two categories, tyre vibrations (due to time varying contact forces) and airflow related processes (e.g. air-pumping) in the contact between tyre and road. The paper only focuses on tyre vibrations. An existing model for the simulation of tyre/road interaction is used to investigate the influence of tyre design on the vibrational energy stored in the tyre structure during rolling. It can be shown that ,although design is changed substantially, very little changes can be observed with respect to input power through the contact into the tyre structure. Changes in driving point mobilities of tyres are not directly related to changes in noise generation. Geometry changes leading to different contact geometry and in this way to different modal composition of the vibrational field as well as design changes leading to changes in wave speed are of higher importance. These changes have a strong influence on the radiation efficiency of tyres.

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