http://s2.photobucket.com/albums/y20...t=DSC00825.jpg
above is a pic of the drive we prototyped, thos are 8"X2" wide rough top ifi wheels, 1 cim per side, with a gearing of ballpark 14:1. We use dthe existing gearbox from our 2006 robot, yes that our shooter sneaking into the pic, hah