Doug,
I've never considered tire speed relative to road speed, but I think I see
what is meant by
the equation. It possibly refers to the road speed added to the tire
rotation speed.
Consider a tire on the car somehow not rotating though the car is doing 55
mph. That tire is going 55 mph with the car. Now rotate it at 55 mph and the
speed of the portion rolling forward (upper) is doubled and the speed of the
portion rolling backwards (lower) is negated.
The front and back of the tire are moving vertically and so are going only
the speed of the car, 55 mph.
How am I doing, Professor?
Steve
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