Think of it in feet per minute. Going around a curve at the same RPM the outer wheel must travel at a greater "Feet Per Minute" in order to keep up with the inner wheel thus eliminating drag. This is accomplished via different diameters of the wheels. On a curve the outside wheel will ride up on the larger portion of the taper and the inner wheel will ride on the smaller portion of the taper eliminating the SKID or Drag which allows for a smoother rolling of the car. On a straight track both wheels would be centered and ride at the same tapered portion of the wheel.
Rod Miller
romiller
