I have the stock 14" wheels on my '59. The spare wears an ancient 7.50 x 14 bias ply, which according to my sources should deliver about 750 revs/mile.
I put 215/75/14s on the stock wheels, thinking they would be a good replacement due to a theoretical diameter good for 755 revs/mile, but it the actual rolling diameter is much smaller due to how much flex there is in the sidewall. As a result, my speedometer and odometer are a full 10.8% off, which translates to a reading about 8 mph too fast most of the time.
I was thinking it might be worth trying 15" wheels to get more diameter with less sidewall, but I thought I'd check in here and see what people are using on comparable vehicles.
Thanks!
1954 Crestline Victoria 312 4-bbl, 3-speed overdrive