WheelHit.collider  

var collider : Collider

Description

The other Collider the wheel is hitting.

// When attached to the WheelCollider, modifies tire friction based on
// static friction of the ground material.
function FixedUpdate() {
    var hit : WheelHit;
    var wheel : WheelCollider = GetComponent(WheelCollider);
    if( wheel.GetGroundHit( hit ) ) {
        wheel.forwardFriction.stiffness = hit.collider.material.staticFriction;
        wheel.sidewaysFriction.stiffness = hit.collider.material.staticFriction;
    }
}