Like Norty1, I have Firestone Transforce HTs on my truck. They are E rated 8-ply tires. I run the GM recommended pressures - 80 psi in the rears and 55 psi in the fronts. I am completely satisfied with them!
The truck came with Bridgestones on it and I went through 2 sets in 74K miles, so decided to try the Firestones, based on a co-worker's recommendation. He has had them on his truck for 15K miles and likes them a lot.
2015 Jay Flight 32RLDS Elite
2012 Chevy 2500HD Crew Cab LTZ (6.6L Duramax/Allison)
Equalizer Hitch (1200# bars)