I have an '07 Yukon and did a 1" level up front (.87" spacer below the lower strut purchase). It still has a very slight rake. When I tried the 1.5" level kit spacers, the truck had a slight squat, so reinstalled the .87" spacers up front. I have the Autoride suspension, so installed a small plate to raise the ride height sensor the proper amount (it wasn't much, like 1/4", raising it's mount position straight up).
With this level kit and a trim on my front valance, I have excellent ground clearance up front (more than what I actually have under the truck), so rarely have to worry about snagging the valance and tearing it off on a big rock on the trail.
I have the optional factory 20" wheels and with the factory 275/55/20 tires and from day one had some clearance issues inside the wheel well at full lock. In time things wore away and now I have no rubbing. This combination is slightly wider than your stock setup and very close to the same diameter. I agree with the advice to stick with 17" wheels, as the sidewall height on the 20's is pretty short and offers little margin for error in unforgiving terrain. I would be very surprised if you could fit anything wider than 275's with an aspect ratio that brings you up to stock diameter, without some heat gun work on the plastic in the wheel wells, at least at full lock.
Good luck and have fun.
With this level kit and a trim on my front valance, I have excellent ground clearance up front (more than what I actually have under the truck), so rarely have to worry about snagging the valance and tearing it off on a big rock on the trail.
I have the optional factory 20" wheels and with the factory 275/55/20 tires and from day one had some clearance issues inside the wheel well at full lock. In time things wore away and now I have no rubbing. This combination is slightly wider than your stock setup and very close to the same diameter. I agree with the advice to stick with 17" wheels, as the sidewall height on the 20's is pretty short and offers little margin for error in unforgiving terrain. I would be very surprised if you could fit anything wider than 275's with an aspect ratio that brings you up to stock diameter, without some heat gun work on the plastic in the wheel wells, at least at full lock.
Good luck and have fun.
