I'm leaning toward MT/R Kevlars.
My 2011 F250 6.7L Super Duty is often my daily driver and is always my tow rig, including a big-*** dual tandem OTW flatbed gooseneck with two Jeeps on it, weighing in at about 15k lbs total. Yes, I have installed airbags to counteract the suspension squat
It came from the factory with the 3.55 gearing and 34's (275/65-20 = 34.1x10.8"), but the dealership agreed to swap them with another truck that had the 33's (275/70-18 = 33.2x10.8").
I want to run something that looks good, does well in mud on a hunting lease, has impervious sidewalls, handles the loads I'll put on it, and generally won't wreck the ride or get super noisy. I am NOT interested in lifting the truck. I could run 37's at stock height (which looks awesome), but I don't want to regear, don't want to destroy my fuel mileage too badly, and I don't want to wear out all the joints and bearings and stuff to quickly--I plan to keep this truck for many years. So I'm sticking to 35's. The sidewalls are important, by the way, because the cactus around here can be brutal; one at K2 poked a hole in the sidewall of the Nitto Terra Grapplers I had on my old tow rig.
I'm looking at Goodyear DuraTrac in 325/65-18 (34.8x13) with max load capacity of 3,860@65 or Goodyear MT/R Kevlar in 285/75-18 (35.1x11.3) with max load capacity of 4,080@80 (both load range E). I will also occasionally have to deal with mud (by necessity not for fun). Both will fit in the wheel well with plenty of space to spare, but the MT/R Kevlar will be closer to stock width.
Honestly I'd rather have the MTR Kevlars but think it would look nice with the DuraTracs as well, though I'm not sure how either would be on the road at first or after some wear has been put on them. I don't want it to be squirmy or all that jazz.
EDIT: A gratuitous pic of the truck and trailer: