Braking force/Wheel slip

The braking force is equal to the friction between the tire and road surface. All braking causes a certain amount of wheel slip. Slip is 0% for a free-rolling wheel and 100% for a locked wheel.

Starting from 0%, the braking force increases rapidly while wheel slip increases slowly until a maximum value is reached. Beyond this value, braking force decreases as wheel slip increases.

The wheel sensors provide information about the speed of each wheel. The TC/ABS control module measures the reference speed; normally the speed of the fastest rear wheel. This reference speed is then used to determine whether a wheel exceeds the limit of optimum slip.

Fig 2: Lateral force as a function of wheel slip.

Y-axis = Lateral force

X-axis = Wheel slip

1. Lateral force
2. Stable
3. Unstable
4. Wheel slip