[70rs/ss]

I think 17-18-20 inch wheels will be OK in a 35-37" tall tire, but the cost goes up as the rim size does!! The good part about a bigger wheel with a tall tire is that you get less sidewall and with less sidewall you get less flex. Sidewall isn't all bad, so find a happy medium with a bigger wheel and some sidewall as a bit of sidewall also cushions the rig. No sidewall is like rolling on rocks instead of rubber tires. I'd think 37s would fit your rig as a 2' suspension lift is OK to get 35s on and with 2"+4" of lift you should be OK. If it is going to be a pavement pounder why use a lift and big tires, just asking as the price of gas seems pretty happy climbing instead of going down, and big tires means rolling resistance and therefor MPG suffers. I am sure you know that already, so I'll leave it at that. Check out tire rack, discount tire, and 4wheel parts for the 37s in 17", 18" and 20" and get an idea of the price difference and go from there. I was going to put a decent offroad, mud snow tire on my 4X suburban with my 20" wheels until I saw the cost of the rubber, ended up using a Michelin M&S tire. 20's are pricey in the agressive treads for some reason??