Research

The vehicle tyre forms the interface between the vehicle and the road and directs the wheel loads and the longitudinal and transverse forces from the chassis into the ground contact area. Due to the high importance of driving safety, the contact between tyre and road has its own field of research. Especially the friction behaviour of separate tread segments or tread blocks have received a lot of attention in recent research. The friction behaviour of these systems is determined by a variety of cause variables. The stiffness and damping characteristics of tread material, the local contact pressure, the roughness of the road, the road conditions and the tread design shape traction and have a significant influence on the braking distance or the maximum level of lateral acceleration. The product characteristics, required by the customers, such as low rolling resistance, reasonable wear behaviour and a good wet grip can be optimised through an appropriate mixture design in regard to material stiffness and damping.

Test drives to examine tyre behaviour are very time-consuming and expensive. However, they are essential to assess the tyre behaviour. The reproducibility of outcomes is a critical aspect, especially when the series of tests cannot be completed on one day. The environmental conditions are not even constant over one day. For this reason, lab tests under reproductive circumstances are a reasonable addition to test drives. It is not always necessary to test the whole tyre with regard to dynamic friction and wear behaviour. In this area, the tests of separate tread bars on friction surfaces provide sufficiently accurate results for a comparison with a reference configuration. Often, experimental friction tests with separate tyre blocks or small, local samples give a much deeper insight into the complicated friction or wear mechanisms than the testing of the whole tyre.