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?