In box2d physics engine I can set a motor speed for a joint on my wheel in Radians/Second.

What would be an expression I could set the speed to so the final actual "speed" of the wheel would be the same regardless of wheel radius.

Presently, I'm setting the Wheel speed as a constant, wheelSpeed = 20. But this has the effect of making large wheels faster than small ones. I want the radius to be used in figuring the radians/sec for the motor speed so I will get the same effective speed regardless.

So, if it was a small wheel, it would have to turn much more often than a large one.

I think I need to do something like 2 \* PI \* Radius / 180 \* Speed? Or something similar, but I can't figure it out exactly.

I want to based the wheel motor speed (in radians/sec) it so the final "speed" of the wheels is constant regardless of size of the wheel.