Yep the largest recommended tire size is what is on the OR model. I'm not sure what that is. Less than a 285 though. And, I do recommend doing that.
Yep, factory rim is 7 in and a 285 75 16 calls for a 8 in. to make it sit properly on the road, otherwise it bulges in the center and runs out of balance.
I like the "LOOK" of the 285 75 16's but I'd say it's a safer bet going with the OR size tire for gas mileage reasons as well as handling, and making sure they don't scrap out your front diff. (That's a rumor that over size tires cause this) 20K and no trouble there, here. MC