60psi should be plenty of pressure for your setup. Check a load inflation chart but probably good for at least 2500lbs per tire
Many causes of cupping, feathering of tire tread and not all of them indicate anything is wrong.
Infrequent rotation
Curvy roads
Too low of pressure, maybe for the sway with a camper or in general
Bad shocks
Bad ball joints
Too much too little camber
Bad alignment
Not tailoring the rotation to how the tires are wearing.
If the truck is in good alignment and good condition then it could be just wear.