True; and I don't plan to replace these tires until they're shot.  But I was wondering for next time, as the smaller rolling diameter also means quite a few more rpms at highway speed.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Change the speedometer gear in the trans - a lot cheaper than buying new tires.

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

The original 7.50 bias-ply was an 80 series tire.  By going to the 215X75X14 you're running less sidewall making the speedo think you've changed rear axle gears.  The tires you're now using are a good fit for the '59 and will give good handling and ride. I'd look for a speedometer gear that can be swapped to give your speedo the correct reading.

Larry D

Winnipeg, MB Canada Eh!


'57 Fairlane 500 Club Victoria

'58 Custom 300 Tudor

'56 Crown Victoria

'61 Starliner Z Code

'51 Ford Victoria

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