Stock tire and alloy rim = 43lb, 31" on steelies = 70lb.

More weight to spin up and more weight to slow down through the tcase. When you lose traction these forces are acting on the tcase. Exactly the same reason you wear out your brakes quicker with big tires (more than you would reasonable expect "numerically" correcting for odometer inaccuracies).

2002 Sporty , Ironman 2.5" spring, 2" body, 15 x 7 ROH wheels, K&N, 15 x 10.5 Simex Centipedes, Powerchip 91.

"Never argue with an idiot. They will bring you down to their level then beat you with experience!"