Trailer Tire Question

harry and thea wrote:
We have a 2014 Rockwood Signature Ultra Light 8244WS fifth wheel, 26 ft 9 in long with a dry weight of 6537 Lbs and probably 7500 lbs loaded. Was on a trip in Northern Ontario last month when I noticed a strange gouge in one of the stock tires. Put on the spare and stopped in the first town with a tire dealer for a replacement.
Stock tires are ST 225/75R15 Trail Express Power Towing made in China load range C with max load 2150 @ 50 psi.
Dealer recommended replacement tire same size Good Year Endurance load range E made in USA max load 2830 @ 80 psi. He said it was absolutely ok to run the new tire at 50 psi along with the remaining 3 original tires. I have been a little uneasy about the underinflation of this tire.

My stock tires are now exactly 5 years old from date of manufacture. So I am considering replacing the remaining 3 tires. I definitely want to upgrade to a higher load range but don't want to run 80 psi for harshness of ride.
If I bought 3 identical tires to the one I replaced and ran them at 65 psi, would that be a good idea? Or would it be better to buy four new load range D at 65 psi and replace the spare with the one bought up north.

I guess the real question here is if it is ok to run a heavier load range E tire at a lower pressure providing you don't have the weight or is it preferable to go to maximum pressure with load range D

Would sure appreciate input from those with tire knowledge.