Back wheels bigger than front wheels? rpm question

[carp]

So i know if you drive a tractor down the road in 4wd eventually the axle explodes because the wheels are difference sizes and 1 axles is pushing the other because theres so much traction on tarmac. My question is does it matter much in scale models? my back wheel has a circumference of 56 and my front 42, if i put gear motors on that all turned at 50rpm would there be problems with the back wheels trying to travel faster than the front?

[Lil Giants]

Actually, in the 1:1 world the front axle is a wee bit faster, it's pulling the tractor rather than holding it back. It's only noticeable when you turn it off.

Having same rpm motors with 25% difference in tire diameters will without a doubt be too extreme in different speeds & destroy the model quickly. Try finding two different gearheads with roughly comparable final outputs to the ground & if one is a little faster, be sure it's the front steerable axle. ;)