Year old thread and I'm a newbie with my new to me 3RD on this site although I've been on MUD for a long time and I expect to get flamed. I've been wheeling since 1974, long before the Internet, and I've owned maybe 12 Toyota's including 6 FJ40's. Not brag, just a bit of history.
My FJC has the Off Road option and came with 16" wheels and I've been running BFG KM2's 255/85R16 on those wheels for awhile, it's a great combination. Oddly enough, I have a 3" lift on that truck.
Just for laughs I put the 16" wheels with KM2's from my FJCruiser on the 3rd. They sure did fill up the wheel wells - LOL!
Admittedly, I don't have much weight in it besides me a box of tools and a couple dogs, but I haven't been able to get it to rub on any of my wheeling ventures.
So my take is this: Don't overlook tire width when going up in size. A 285/75r16 in a KM2 is only .2 shorter than a 255/85R16 which is a full 33" but it has a 1.3 wider section width which is the main reason they rub without a fairly substantial lift. I haven't checked the specs on my wheels, but they might also contribute some.