During cornering, centrifugal force acts on a vehicle to produce a side force. This side force must be resisted by the interaction of the tire on the road surface. The greater the side force, the greater the opposing force must be.
Without this resistance, the vehicle will continue in a straight line.
The pneumatic tire provides this opposing force by being able to distort while still gripping the road.
Then since the tire’s construction makes it elastic, it exerts a force, called cornering force, which acts between the tread and the road surface. It pulls the distorted rubber back to its normal position.
The tire’s sideways distortion makes the vehicle follow a path at an angle to the direction the road wheel is pointing. This is called the slip angle. As cornering force increases, so does slip angle.
When a vehicle is being driven into a turn with decreasing radius, both slip angle and cornering force increase, until a point is reached where the tire slides, and the only resistance comes from sliding friction across the road surface.
The tire grips again only when the vehicle has slowed, or is making a turn with a larger radius. That is, when the side force is reduced to a level the tire can withstand without skidding.
Since both front and rear tires develop a slip angle in a turn, the vehicle’s path is determined by the steering of the front tires, and the slip angles of both the front and rear tires. These slip angles depend on the location of the major components.
