Every LT tire makers website I see starts at 35 psi at around 1800 lbs and goes to 80 psi at 3195 lbs.
I use 45 psi in my rear LT265/70-17 E Michelins on my 2500 Dodge truck when not hauling. With only 2900 lbs on both tires = 1450 per tire that = 35 psi and works great. Ran the 1st set up to 115k miles.
On a 2500 chevy 5.7 with stock LT245/75-16 E I use 35 psi when not hauling. I generally ran tires on that truck up to 75k miles on average. With 235k miles this truck has had several sets of tires on it.
I had a set of LT235/85-16 E Transforce HT on a GN flatdeck trailer. They lasted 11 years and probably 50k-55k miles before I got scared of the sun checks.
