This is just a matter of knowing the formula for the circumference of the circle and doing a lot of unit conversions. I'll do the case where the wheel is traveling 5 mi/hr and let you do the others.
The circumference of the circle is
so the distance between two teeth is
The wheel is moving at a speed of
So the pulse rate is
I'm assuming the teeth are along the edge of the wheel. If that's not the case, you need to clarify your question.[/edit]