Wheel shown is not a Firestone "widomaker" wheel. Tire is weather checked so should be replaced. I haven't looked for 20" rubber for many years so I don't know what's out there or prices. But I've seen many big trucks at the ATHS shows with good new 20" rubber so tires are available. You might look into joining ATHS. Lots of support, and many owners still work their trucks. American Truck Historical Society.

1951 3800 1-ton
"Earning its keep from the get-go"
In the DITY Gallery
1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.