65 vs 80 PSI depends largely on the load on the tires. My SRW 18” Tire’s with camper on are set at 80 psi and my camper is heavy. Really heavy, I’m over weight on tires and axle, so I run them at max pressure and watch the TPMS like a hawk and feel the tires at every stop to check for excessive heat. Heat is a big concern when you start lowering tire pressures because lower pressures add flex to the sidewalks and thereby adding heat. To much heat can cause a tire to fail. Your best bet is to weigh your truck and see how much weight on the tires and determine if can safely run at 65 psi.
