I just made the switch from 285/75R16 D STT's to 255/85R16 E Maxx's, and I couldn't be happier!!! The ride is BETTER, not worse, and the tires are performing awesome!! I think the sidewalls are no stiffer than my old D's, which jives with what I was told by Cooper at SEMA this year. I don't miss the width at all, and mileage seems a little bit better. The Maxx's don't make noise. I'm serious. I can't hear a thing out of them. The new Fun Country's that I have HOWL by comparison. Performance offroad in Moab and Colorado has been stellar, equal to or better than my STT's in all respects. I suspect that the STT might be the better mud tire when the going gets snotty, but I just don't see much mud anymore.
I mounted them on the same 8" wide wheels that my 285 STT's were on, and they look right at home. The Maxx's tread width measures closer to what would be considered a 265 tire, just like the Toyo MT.
Chris