thats funny...my 1942 gmc dually sat for 20+ years and those tires are still holding air on the original split rims!
I agree :Handshake I had a 48 Ford coupe that had tires on it that had been on it since sometime in th early 60's that held air the whole three years I had the car. I also had a 38 Chrysler coupe that had what looked like tires from the 50's on it. It had sit for years before I got it. Those tires held air for the 5 years I had it, moved it several times, and one finally blew out when we were pulling it out of the building to load it for the new owner.
if the tires don't look rotted all the way through. try to air them up. if 1 or 2 air up you're better off then you were before. take the ones off that didn't air up and run to a tire shop and have them throw some old cheap tires on the rims. at least it'll get you where it'll roll.
wouldnt be the first time i was wrong i would just have assumed they would permently bent into that lop sided shape by the steel inside the rubber
I helped a buddy load a 49 Studebaker up once. We pulled it out of an old lady's shed. Car had something like 7,000 miles. Still had the original tires. That was about 20 years ago, or less. Tires still held air.