We've got the 480's on the rear axle as well. The taller the tire is, the better it will go through anything. That's just plain physics. On the 9610s you can adjust the height on the rear axle one bolt hole. We always had them set high. That makes the sieves work a bit harder and therefor clean better. Have you ever had a two wheel drive tractor with a loader on in the mud and watched the little front wheels stall. Take a front asissted one instead. Without even switching on the front axle it will walk through that mud hole, just because it has taller tires on.