I talked to a couple of places today and they said without spacers between the duals in the rear about the best I could do is 265/70/17 which isn't much taller than the stock 245/75/17. I'm definitely thinking about upgrading the tires, but after thinking about it the truck is almost level right now, what I'll probably do is pull the stock 2" block out of the rear and replace it with a 3.5" or 4" block from a 350 srw. I'm thinking this will give more rake and when it does squat it would be level instead of lower than the front.