2010 - 285/65/18 on stock rims
Just to add to the plethora of info I searched for weeks when I was looking into leveling kits and tires. This truck has a rough country (RC) 2" leveling kit and a RC 2" block in the rear which provided 3/4" lift (the stock block was 1 1/4" ). The leveling kit made the the truck exactly level with nothing in the bed, but as soon as I put in my dogbox in the bed (100 lbs) it sagged 1/2" giving it the cali look. The lift (s) stiffened the ride up just a little. It no longer "rides like a cadillac" but it DOESNT ride like a log truck either.
I searched alot of sites wondering what size tires would be the best fit. I narrowed it down to 275/70/18 (33x 11) or the 285/65/18 (32x 11.5) for stock rims. I opted for the 285's as I wanted the wider look because I have after market mud flaps and I wanted them as UN noticeable as possible. Chevy I think dropped the ball with the design of the new trucks. I live on a rock road and the stock tires threw rocks terrible, nicking the paint in 100's of places. Hence the mud flaps and the new Nittos. They dont throw rocks bad at all. Also, I dont *think* the 275/70's would have fit without trimming some plastic, with the 285's there very little clearance.