[KenWittlief]

someone else mentioned you need to be able to spins your wheels if the bot is against the wall - so you dont pop your breakers

but there is a little more to it - if you look at the RPMs vs current draw, you have to not only keep your motors from stalling, you have to keep them spinning above the point where they draw 40 amps (preferrably well above that point so they are only drawing 20 amps or less, or they will heat up quickly)

thats why you want your motors to be geared down lower than 'necessary' - so you can spin your wheels when push comes to shove, and keep spinning them for a while without cooking the varninsh off the windings in your motors.

It has a very pungent aroma - once you've caught a wiff of it, you will never forget what cooked motors smell like.

btw - the reason why you need to be able to spin your wheels is, the point at which they start to spin or slip is when you have reach the max limit of your friction with the carpet - so if you design a drivetrain that has all kinds of friction with the carpet, but you dont have your gear ratio low enough to reach the max point, then it goes unused - if you dont have enough torque to break the wheels loose you cant use your wheels to their max force.