Right now, we have stock Continental 275/65R18 123 tires (max 3,415lbs) with 10K miles on them. They are mounted to stock aluminum 18"x8" 8x170mm rims (max load 3,590lbs). They are inflated to 75psi ...
I had the same size stock Continentals on my F250 and on two of them the tread separated and they developed bulges about a year apart, with less than 33K miles on them. Replaced all four tires with Michelin Defenders that are rated at 3600 lbs. 50k high mileage street tread design tires.