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 ...
Discussing tires and not knowing the actual weight of your camper loaded is something that should be considered.
Ignore dry weight or even wet weight. You need to weigh that truck and camper loaded with water, and all the STUFF! You will be surprised. Probably coming in at about 4,000 lbs.