Alot of guys on other forums love the 255s but I have no personal experience with them. I know for a fact that load range E 265/75/16s will crown. Seen a set of C plys that did not on a 92.But honestly, you should not be running C or D ply tires on that rig

In MY opinion, determining factor for big(er) tires is if the frame is cracked near the steering box. Big tires theoretically put more load on that weak spot and there is no good AND easy fix now. There is a nice kit by member jungle on RCC but you have to go crossover steering and the alternative factory fix/brace is a junkyard only piece. I've seen one on ebay in the last year. Just not easy to get anymore.
Even if its not cracked YET, I still would brace it.