I have a '98 GMC 2500 Sierra. My tires are 315/75/16's. What size wheel...(width, backspace...if any) do you folks suggest? Truck has a 3 inch body lift too. Thanks for any advice. I believe the wheels on it now are a 6 or 7 inch, and the tires just don't look like they're making full contact on the road with 40lbs. of air.