It is true that the tire manufacturer recommends 7.5" wide wheels as the minimum. However, there are many GM trucks running 285s on stock 6.5" wide wheels (some carrying campers, many pulling heavy trailers), with the opinion being that the center tread may wear a little faster than the outside tread because the tire is narrower at the bead, thus pushing the center tread up a little. There is no magic in "getting away with" running 285s on 6.5" wide rims. It was simply done. Mostly because I, like everyone else, could not find 3800 lb >7.5" wide wheels in the aftermarket, and I did not want to go to 19.5s. I accepted that tread life may reduced a little; however, in my case, the first set of Goodyear Wrangler Silent Armors lasted over 50,000 miles, most of them carrying the camper on the truck, usually going down the road as much as 11,620 lbs fully loaded and wet - 4840 lbs on the front axle and 6780 on the rear axle, weighed on a CAT scale. I never had a moment of trouble with the tires and we traveled many miles on Forest Service Roads and quite a few primitive roads too (low range, low gear) as well as highway travel all over the West. I even hit 95 mph once, with the camper, passing on a 2 lane highway around a line of slow cars - I never drive that fast and cruise at about 63 mph, but I looked down and the speedometer was on 95 (BTW Silent Armors are speed rated to 105 mph). The second set now has about 7,000 miles on them and are also doing great, with the same travel profile as the first set. Goodyear Wranglers are premium tires, but probably no better that other mainstream name brand tires. As for me, they have worked out wonderfully. Please note, that for my model year truck (2007 Classic GMC) I did have to trim the front plastic air dam a little to keep the tires from rubbing and CHOOSE to do a 2" leveling lift to get more ground clearance, not to clear the tires. For most, probably the best piece of mind will be found fitting 19.5s, but there are trade offs, such as cost, harder ride empty, etc. I am happy with my choice of 285s on stock PYO wheels and have as good a tire track record as any truck camper on the forum. Terry
