The term “Tyre Force” generally means the total force exerted by the ground on the tyre. This force has lateral and longitudinal components for a driven tyre as shown in the diagram. These components can be further resolved into the central and tractive forces. It is essentially the central force that provides the centripetal acceleration of the car. It is the tractive force that determines whether the car rounds the corner at constant speed or not. The distinction between these forces their magnitude and vectors are often overlooked by students of vehicle dynamics. As we will see later their importance is vital when related to the vehicle in motion. Three situations are shown below:

• Combined driving and cornering
• Pure cornering
• Combined braking and cornering