The Influence of Tire Properties on the Stability of a Motorcycle in Straight Running and Curves

This paper presents a numerical analysis of the modal properties of a motorcycle, in both straight running and curves. In particular, the importance of tire on the stability of a sports motorcycle is dealt with.

The analysis was carried out using an eleven degrees of freedom model of a motorcycle, which describes both in-plane and out-of-plane dynamics. A detailed tire model, which takes into account both the geometrical and elastic properties of the tire carcass, was used. The properties of the tread rubber (like pneumatic trail and twisting torque) were considered, as well as the properties of the carcass (like size of cross section and carcass stiffness); their effects on natural frequency, damping ratio and modal vectors were analyzed.

Furthermore, this paper deals with the interactions between in-plane and out-of-plane modes during steady state cornering, regarding root-locus and modal vectors.