I thought there was some kind of standard that said D rated aired to 65 and E rated aired to 80, just because I've never seen any deviations from that, but it just goes to show that you don't know what you don't know....I'm always learning new stuff here on the forum and I appreciate the comments and expert opinions.
Buying a used truck is always a compromise...I was willing to accept the 1.5" coil spring spacers ("leveling kit") and oversized tires to get a truck with no rust, documented dealer service over 5 years from a single owner, no accidents, no evidence of aftermarket tuning, and overall really clean.
I was expecting to be hugely disappointed with these tires in terms of traction (contact patch too large), noise, vibration, and squirm under load. To my surprise the truck is quiet and smooth as glass at 70 mph, very stable with 3100 lbs of camper in the bed, and very sure-footed on wet roads. Snow performance is TBD...
There is evidence of rubbing on the front trailing arms at max steering angle (full lock) but no wear or damage to the inside sidewalls.
The rims are OEM and in great shape, no scratches or pitting at all. I haven't decided whether to get wider rims or narrower tires, but I probably have another year to figure it out.
The leveling kit makes the truck look badazz when empty, but it sags a little in the rear when loaded with the camper. I can't lose the leveling kit without first going to smaller tires, and my alternative is adding air bags in the rear if I stay with this size and go with bigger rims with the proper offset to avoid rubbing.
My main concern was running fully loaded at only 65psi, but sounds like I'll be OK for now.