Probably a waste of time, but:

Whatever is on the door sticker goes out the window when you take the factory tires off, and you sure as hell don't run the "max" pressure unless you are loaded to the max. Are you carrying 7200 pounds on this trip? Mine are stamped 3200 each x 4 minus the weight of the truck, and that's what I would have to be hauling to go to 65 pounds.

Go by the bulge of the tire and the wear pattern, every tire is different.

My Michelins are "D" rated on my 5600 lb QuadCab I settled on 46 front, 44 rear. Lots of long distance trips with 800 pounds in the back at those pressures as well.

Only time I ever put 60 in the back is when I'm towing a 7000 pound trailer.

For those who are certain to argue with me, here: 161,000 miles on these tires, see any problems?