Anybody done a 19.5 wheel conversion ?

The late moderator on one of the other forum boards Sir Drake (RIP) did the conversion you propose on his 2004 3500 using Rickson wheels. IIRC, his 3500 was a SRW. I had pm'd him for his experience because I pondered doing it when I owned a fifth wheel. Believe he had a Lance TC and he said ride and handling were fine and the conversion process pretty straightforward.

My 2006 3500 SRW (Cummins, 6 speed, 3.73 gears) wears Vision Hauler 81s (black) with Sumitomo 19.5s. It rides a little rougher empty but only marginally so. Towing my 10K pound trailer it rides the same as OEM towing the same load.
The tires stick out of the fenderwells a little, I have old vs. new pics for reference but don't know how to post them to this message. I'm running 245's, they made a 5 to 6 mph speedo difference at 60 mph with no ECM flash required.
My reason for the upgrade was my fifth-wheel (on order) pin weight will be 3500 pounds and the OEM tire limits will be exceeded.
Reference the weight police, the combo is within legal limits; 20K pounds per axle or 500 lbs. per width-inch of tire. The door sticker means nothing (some states value GCWR, no state that I know of adheres to any axle weight limit other than the above listed).
Good luck with your decision, your truck capability and safety will be enhanced if you decide to make the change.

Vision and Rickson make 8-lug rims for 19.5" tires. My F250 typically hauled 7000-8000 lbs on the Sterling 10.5" rear axle running the Vision Heavy Hauler rims with 19.5 DynaTracs.

Definitely check the truck camper forum. I was hauling a 4000 lb truck camper while towing an 8000 lb enclosed trailer with my F250.

Check out our truck camper forum as its a very popular upgrade for carrying those heavy 4k-6k TCs.

I don't know what the difference would be, but my 2013 GMC 2500 came with 20" wheels and load range E tires. Handles great empty or towing the travel trailer.