I'm running the same size, but I did a 1.5" level shortly after getting the truck, with no difference in ride quality over non-leveled. After the stock Goodyears wore out, I replaced them w/ Cooper Discoverers in 276/65R18. Only a couple of pounds heavier than stock, so very little hit to gas mileage, and still rides good. WORLD of difference in traction on wet roads and light mud over the stock tires.