It has nothing to do with the number of tires on the car. A skid is calculated with the coefficient of friction. Meaning how sticky is the road. Well polished asphalt is lower or slicker than new etc. Water naturally lubricates the surface.
Generally the mass of a bike is far less than the mass of a car or truck so things stay pretty equal.
The friction or coefficient of friction is determined by a drag sled or other form of measurement. But, we are dealing with once traction is broken. We are not talking stopping distance. We are talking recovery of traction. Once the tire skids it is floating on the road, it cannot be steering in a skid until traction is applied. That is ABS. It gives traction back.
To me its just a no brainer.
