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 went from the OEM tires on my F350 gas 4x4 to 245/70R19.5 LRH Continental Hybrid HD3 mounted on new Rickson steel wheels. Wheels rated for 5000 lbs and tires for 4940. About an inch bigger. In Tow mode I don't feel much difference in engine performance with the 3.73 ratio. The tires are stiffer and feel more stable. Also more tire noise and the higher pressure makes for a harder tire, I would like to find a 150 gal water bladder to add ballast when the TC is not aboard.