What is correct tire size for 1974 Ford torino?

Answer 1

Base model Torinos (including Gran Torino and Gran Torino Brougham) came with GR78-14 tires, which translate to 205/75R14 in metric sizing.

All wagons and Gran Torino Sport models came with HR78-14 tires, which translate to 215/75R14 metric.

Optional tire sizes include:

HR78-14 (215/75R14)
HR70-14 (225/70R14)
HR78-15 (225/75R15)
HR70-15 (235/70R15)

Translations are rough but are pretty close. It's hard to find a lot of these sizes with strong enough load ratings to carry these heavy cars so many other sizes can be substituted.

For example, my '76 Gran Torino rides on 215/70R14 tires because they are common on Aerostar and Ranger models from the 90's and are still widely available. My speedometer is slow by about 3-4% because of this. Switching to larger wheels might help you find tires easier. 225/60R16 tires on Crown Victoria steel wheels would be closer to the stock HR78-14 diameter and are a VERY common modern size and that is what I will switch to when I can no longer find suitable 14" tires for my car and its current wheels.