The 7.50x14 and 8.00x14 sizes were common back then. 7.50x14 went to the mid-1960s size of 7.75x14 size, F78x14 (think base 1968 Furys and optioned Belvederes). P-Metric would be P205/75R-14 radials. 8.00x14 might be considered a "station wagon" tire back then. The 8.25x14 and G78x14, then P215/75x14. The factory rim width would have been a "wide-base" 5.0" or possibly 5.5" wide wheel (measured INSIDE the bead surfaces). So, very narrow by modern standards, or even 1990 standards.
In the 1957 Dodge FSM, the 7.50x14 is listed for the smaller/lighter Coronets and the 8.00x14s are listed for the more upscale and a bit larger/heavier cars. 14x5 wheels for the Coronets and 14x5.5 wheels for the larger Dodges. SO, those sizes are big enough to "carry the weight" for those cars. Which WILL be verified by the spec charts in
TireRack.com for tires of those sizes. For example, a modern P225/70R-15 size is rated at about 1750lbs at max inflation pressure EACH. Which extends to 7000lbs for all four! Nearly double of the base car!
At the present time, in currently-available 1966 white sidewall widths, I believe the P215/75R-14 size is still around at "decent" prices from a few "normal" tire brands. Going into the wide white wall orientations can nearly triple the price, by observation. To me, no need to spend over $1K/4 tires for a car which will sit a lot of the time (i.e., not daily use by a long shot). It's bad enough to have to pay $500.00/4 tires already, to me. But then I remember getting Radial TAs in the P225/70R-15 size for $75.00/each in the early 1980s! BTAIM
To me, a factory wheel which might look good on those cars is the 1970s Rallye Wheels. Common in 14x5.5" sizes on A-, B-, and E-bodies. Which also expanded to the 15x7s on big-engine E-bodies, then 15x6.5 on 1976 Charger SE cars. Available in repro if none in older salvage yards.
Personally, I would find some currently-available P215x14 whitewalls with some factory tubeless-tire-rated wheels and never look back. If opting for blackwalls, then hubcaps (of some sort) too. Setting the tire pressures at 32frt/30rr cold, too. Add a bigger front sway bar, some good HD shocks, and even a rear sway bar if possible. Then pep-up the standard V-8 with some modern upgrades (electronic ignition and late-model carburetion), an alternator, etc. The standard rear axle ratios should already be in the "performance" ratio range, as I recall . . . compared to the later "highway gear" orientation. A good (reasonably quiet)2.25" exhaust system. Line the floors with DynaMat or similar. A 1970s-style floor-mount Pioneer stereo. Make sure all if the condensate drain holes at the corners of the front and rear glass are connected and open! Then an under-dash a/c system. Then . . . look for some open road. Of course, modern power steering and power brakes in the mix, too.
When I was in my pre-K and younger years, my parents bought a new 1956 Plymouth Savoy 4-dr sedan. Six cyl, 3-speed, radio, heater, white walls, wheel covers, AND two-tone paint. It served our needs well, back then. So one of those "soft spots" for me with those cars.
Enjoy!
CBODY67
