Slip is generally recognised as the point at which a tyre, under harsh cornering or braking, loses its adhesion at the contact patch. Different tyres will, according to tread pattern and compound, have different levels of slip and it is also affected by road surface.
Diagram shows a tyre undergoing lateral forces. The red area “A” shows where the force (slip) is being generated.
Slip will occur at a much lower value on a wet or damp track than on a dry flat surface.
In this section, the term slip angle should also be mentioned. Slip angle is best described as the difference between the angle of the steered wheels and the direction in which the tyres want to travel.
This diagram shows a typical example of slip angle. The angle marked a is the difference between the steered wheels’ angle (red) and the direction in which the vehicle wants to travel (blue)
Excessive slip angles will lead to an understeer situation (front) or oversteer (rear).