80 psi in a 3750 lb rated tire on a F250 with a 6100 RAWR with approx 5400 lb load. Thats not the best idea.
Your F250 may have a 3000 lb unladin rear axle weight
Your 12000 GVWR trailer may have a 2400 lb pin weight.
Together = 5400 lbs on your trucks rear axle. Now look at Norskeman pressure/capacity chart numbers he kindly posted for your to use.
It show a 55 psi for 5500 lb load. Lets add a bit of reserve pressure say to 6100 which is all your trucks 6100 RAWR.
Now you can use 65 psi for your max load for those large optional tires.
If you had OEM LT265/70-17 E at 3195 lbs capacity then,as I do, you could use the full 80 psi if needed.
