run them at around 40. I run my at2's at 35 or so. Its personal preference, and judging how they are wearing though. 80psi is for if you're running them on a 3/4 or 1 ton and pulling a heavy load.
I believe there is a "chalk" test. you take a chalk and draw a line straight across the tire, drive forward and if the chalk is on the sides but not the middle, you're too full of air, something like that. idk lol
I run my E rated tires to where when they're hot they're at 42-43 psi (39-40 psi cold). That's seemed to give me the best feel for the road without being sluggish or overly bumpy. honda's tip of drawing chalk across the tread will let you know the wear pattern: no chalk in the middle is wearing in the middle, too much air. No chalk on the sides too little.
I lower/raise the pressure depending on the material I'm driving on if it's off road.
I'm running LT275/70R18 BFG TA KOs (1st gen) on my T for the last 10k. They're E load range tires, as most in the LT in that size are. I noticed last night my fronts are a little low due to the temp drops here recently, but I've had great performance out of mine setting the fronts at 42 cold, and the rears at 35 cold. Everybody said my TPMS would flip out but so far, I'm still getting readings on all four tires, and no warning lights or anything. I'm also getting even wear both in the front and back, which is how I got to the different pressures. We just don't have much weight on the rear, compared to the front. I'm in a 2011 CC so I should theoretically have the most even weight distribution, but its still biased forward quite a bit.
I swear by BFGs, ever since my first Nissan back in 01. Always had BFGs, ran them at 35 year round, no trouble. This 2015 Titan came with Continental ContiTrac and I'm unimpressed. I have no confidence in them. I'm slipping on wet roads, what will it be like when the snow comes down? I dread winter, and can't afford $1000 to replace them.