"What was Jayco thinking when they selected a load range E 80 psi tire for a big 16500 lb trailer. Especially a Endurance with those thin 8/32" of tread depth."
First thing what the HE!! does the tread depth have to do with the tires capacity?
Let's do some math. Let's assume a minimal 20% pin that would mean 13,200# on the axles. Take that by 4 and the per tire load is 3,300#. The ST 255/85 R16 has a rating of 4,080# @ 80psi. I think a 780# cushion is plenty.
GY intentionally built the tire with 8/32" tread dept to keep the tire running cooler and they determined most RVers will age out their tires well before they wear them out.
I run them on my Boat trailer and 4 years and well over 20k they still have plenty of tread left.
You always are thinking Commercial and i understand that.