Vibrational Performance Differences Between Tires with Cross-Biassed Plies and Radial Plies

In order to outline the differences in vibrational performance of cross-biassed and radial tires, the principal types of vibration present in a running car, for which the tires are fully or partly responsible, were surveyed. Then the mechanical parameters which define tire behavior were stressed. Referring to two types of tires, one radial and one cross-biassed of the same size, the values assumed by various parameters (such as vertical and lateral dynamic stiffness) and vertical complex transfer functions are presented, including the frequency spectra of the oscillations of two different cars tested on the same road, alternately equipped with both types of tires. The frequency spectra clearly emphasized many differences between radial and cross-biassed tires, and demonstrated the existence of tire-vehicle interactions which are dependent on the structure of the vehicle itself. This information should be useful to the car designer in order to adapt the structure of the car to the particular type of tire chosen.