Cranked Keys in front to about 1 1/2" over stock, and slipped 4 extra leaves in the rear packs to gain about 2 1/2". The extra leaves did stiffen the ride a bit, but it also lessened the body roll in corners.... and I can easily carry a LOT more weight, have done over 1600lbs without bottoming out.
285's on stock offset wheels would have cleared fine, but mine have an inch less offset, so they rubbed - nothing a little Sawzall work didn't take care of! A 3" body lift will allow me to EASILY clear 315's (35's), I've got almost an inch of clearance now with the 285's (33's) at full compression.
And best of all.... I got the extra leaves out of an older Suburban I already had. The only thing I had to pay for was the longer U-bolts to clear the 4 extra leaves, they ran $65 total. Even if you had to go and get leaves at a pick-n-pull, I don't thing they'd run over $100.