[ngreen]

We know their is much more than wheel size but is does help in several ways. Higher clearance and more lift by an indivual wheel. We are testing 8 wheeled designs. 3 driven and 1 not. From are test we might be able to use eight but it is much smoother with 10 for us. and a inch in height will not through our center of gravity off much. Using four wheel drive you could climb the step with two wheels. The robot would have to have a lot of clearance and large wheels, say bigger than 12". Two wheel drive with casters would be hard, it might be possible but I wouldn't reccomend it.