Well, according to the sticky...
In my experience I have the UpCountry as well (no sag on mine) and I added 2" pucks. I am running BFG 31x10.50x15 with minimal tread on 5.9 wheels. I have no clearance issues except the control arms at full lock of the steering. And I've stuffed mine to the point opposite corners were off the ground. Mind you, I've never run disconnected.
For 285's you're going to need another inch to inch and a half lift (265 16's = 31" 15's, 285 16's = 33" 15's).