Last year I replaced the 200 x 50 tube. A few days ago it was low and I pumped it up to 36 or so pounds according to max pressure on the tire.

The next day the tire came off the rim and won't stay on even with much reduced pressure. Can't really complain as could have been on for 20+ years.

In the interim I just bought a Princess Auto (Canuck for Harbor Freight) solid rubber wheel that I hope can be made to work with a few extra washers.

Does anybody know a decent supplier for dolly tires?