When the slip ratio is 0%, the vehicle speed corresponds exactly to the wheel speed. When it is
100%, the wheels are completely locking (rotating at a zero speed) while the vehicle is moving.
The braking effectiveness is represented by the “coefficient of friction” between the tire and road
surface.The larger the coefficient, the higher the braking effectiveness. The diagram below shows
the relationship between the coefficient of friction and the slip ratio for two different road surface conditions
(asphalt-paved road and icy road), assuming that the same tires are used for both the conditions
and the vehicles are moving forward. Although the braking effectiveness (coefficient of
friction) depends on the road surface condition as shown and also on the type of the tire, its peak
range generally corresponds to the 8 — 30% range of the slip ratio.
The ABS controls the fluid pressure to each wheel so that a coefficient of friction corresponding to
this slip ratio range is maintained.