Sorry I'm late to this, but I could not have run a 33" tire stock without it rubbing like crazy. As my truck sits now, the 33"s already rub when in reverse or have the steering locked one way or the other. I'm not saying it can't be done, I've seen 35"s on a level around here somewhere before. I just can't imagine it not rubbing like hell when turning. My mpg dropped from around 13 city on stock suspension/tires to around 10-11 mpg city on a level and 33" BFG's. 3.73 rear end. I don't get on the highway enough to have accurate numbers for that, but I have noticed the motor turns slower keeping 70 (65 on uncalibrated speedo) than it used to, dropped from around 2100 rpm to around 1950-2k rpm. So I would imagine what ever gain from the motor turning less will be negated by the tire rolling resistance.
Keys and spacer were from a readylift kit, ordered the 2.5" keys and a 1.5" spacer. It all came in a kit, had local Ranch Hand put it all on. Mine leans towards the back "Cali Lean" ever so slightly.
If you were going to run a 35" tire, I agree with the previous posts. You're going to need 3" lift knuckles for the front, and whatever size spacer you want for the rear, on top of Ford keys(Or any other lifted key). Silverado knuckles work on the Tahoe, just keep to the same year as your Tahoe. I believe the easiest bet for knuckles and spacers is eBay, I have yet to see a kit specifically for the Tahoe.
As far as autoride goes, I believe it does mess with the lift. I *think* you need a specific kit that is compatible with autoride, or eliminate the troublesome system anyway. As far as I know, it has air bags that inflate and deflate along the suspension to raise and lower the vehicle to keep it level. So, I would think there would be a compatibility problem there.
**Edit**
I found the link to that 4" spindle lift that is for a tahoe/yukon NBS. It is here:
http://cstsuspension.com/chevy-pero...8-lift-kit-1999-2006-1500-2wd-suv-4-inch.html
