Guys dont worry about the tire size, this is a problem on alot of trucks including mine. First time they changed the gearbox it was only at 3000 miles with stock tires. Second time it was 53,000 miles with 325-17-70's and they changed it again including the power steering pump. Just show confidence to the service writer that you know what your talking about, because they will try and tell you its the tires when its not.
If they give you a hard time just print out every thread on this problem and show the service manager (proof is in the pudding) that this is a problem on most trucks.
Jake