Best to find tires in yards with wheels and all. Don't worry about cracked sidewalls too much, they have tubes and will last long time. I've had several of these and hacked and cut up the wheels and tirs to junk! No one close wants them, and too heavy to ship cheap! There is an army store listed on the web at
www.auto-rv.com near INdiana. It shows tires with little wear, tube, and flaps for $25 each! This is lugged militar tread, but that's cheap! Maybe you have a Military truck place or such near you? Finding someone willing to change them is a problem too, that's why I buy wheels and all and switch. The later model HD3500 and some Motorhomes and P-chassis delivery trucks have same 10-bolt wheels in 19.5" tire size, one piece! Can use radials. That's what I had on my 54. 53 and down have a smaller center hole, but the lugs are same. Again, will work for rolling at least. I was always gonna see about turning a spacer on a lathe to tack weld in too big wheels for older trucks.