[Ryan F.]

I actually think that if you'd look at it, many of the more sucessfull teams have used smaller wheels on their robots. With a larger or wider wheel you sacrifice manuverability. Also when you start getting into some very large wheels, you'll have much more of a tipping issue. The robots I've seen that used wheels almost wheelchair sized all seemed to not be able to stand upright. You could probably help to compensate for this if you mounted the wheels high on the robot, but then that complicates your design.