Michelin commercial tire lifespan

Grit Dog,...correct,...not 220,....120 psi (typo)

run them. 10 years is the life span

Nice setup though!
AF 811/860 is my fave camper. Big camper features and short bed ready!
If it helps your peace of mind, I hauled our AF860 all over the country on cheapo weak, squishy sidewall, 5-6 year old OE takeoff Firestones. Without issue. Running 75mph + consistently on the open road.
I’d trade a brand new set of those tires for your old 19.5s, today, and be even more confident!
As long as they aren’t dry rotted.

Note, you can’t see some dry rot on fully inflated tires.
Try this. Deflate one of the tires on the truck until almost flat and see if there’s any cracking in the bottom part where the tire is flexed. If not, good to go.

Well they’re not 220psi tires, but aside from that, it’s more about the condition of the tires than the age, at only 7 years old.
7 years parked in the sun in Arizona = throw them away, yesterday.
7 years with fairly regular use but parked in a garage in Ontario likely means they have more years left in them. I wouldn’t even think about replacing them if they haven’t seen an inordinate amount of UV exposure and aren’t showing any signs of dry rot.