Wheel Size Question.

I have these rims on my 71 Demon and Dad runs the same rims on his 69 Barracuda - Wheel Vintiques 63-585404 Wheel Vintiques 63 Series O.E. Chrysler Black Wheels | Summit Racing

We are both running 275/60R15 Firestone Firehawk Indy 500 tires. Both fit without any issues.