AUTOMOBILE DIVISION PREDICTION OF THE COEFFICIENT OF FRICTION FOR PNEUMATIC TYRES ON HARD PAVEMENT

The relationship between the coefficient of friction and the slip of a flexible wheel, such as the pneumatic tyre, plays a major role in the design of refined braking systems for vehicles. The available data being partly empirical in nature, it was desirable to be able to predict this relationship. In this paper an attempt is made to explain the mechanism defining this relationship for a pneumatic lyre operating on a hard pavement. The distinct roles of the flexibility of the tyre and the sliding of the wheel are identified and utilized in predicting the curve. A model of the tyre is proposed to explain the role of flexlbility of the tyre. It is shown that the procedure suggested here can clearly bring out the effects of some of the operating paramenters of the vehicle, such as speed of the vehicle, presence of contaminants in the contact patch. stiffness of the tyre, and vertical load on the wheel.