How to calculate speed and torque

[maddox10]

You want a 5-1 ratio then.

Meaning the gear on the motor needs 5 times more teeth than the one on the wheel.

That will give you a theoretical end speed of 16.5km/h. A tad fast for the motors.

I would suggest a 3.5-1 ratio. End speed 11.5km/h
If you need more speed, you can always go 36V.