If you are looking for height, the 255/85 16's are slightly taller then the 285/75's. They are also a bit narrower - not sure where the potential rub points are on the 2wd's but the narrow width of a 255 might help. I couldn't find 255's in anything higher then load range D though, if thats a factor for you.
Also, if you have the mag hytec rear end cover, I have heard you may have clearance issues with the spare.
Good luck, and let me know which way you decide to go and how it works for you. I'll be facing the same decision in a few months.
-Vic