More gearing and rollout questions

[dog8spam]

I need to know when going from a high turn to a low turn motor will the pinion need to get bigger or smaller? Is there a way to find out how much or what rollout low turn motors will need?

Im desinging my own truck and need to figure out roughly how much space Ill need for different pinion sizes.

[SS Pede]

Lower turn motors require smaller pinions. The rule I've heard is the pinion should be 2 teeth smaller than the number of turns of the motor. 17T motor = 15 tooth pinion. Of course, this is just a rough starting point. Experimentation will be necessary to find the best setup.

[dog8spam]

What car is this with?