[Dick Linn]

Although I'm not sure just where the center of balance is on our 4-wheel drive 'bot, we put "slipperier' poly wheels in front to assist turning, and pneumatic rubber wheels in back. This may have helped shift the pivot point to approximately 1/3 of the way between the rear wheels and the front. We wanted to avoid drivetrain stress and assist turning but gain a bit from having the extra traction on the ramp. So far, it works very well.