1965 gt350 clone tire question

I don't think you would want to go any taller than 70. 80 would be next size up.

The sidewalls on the original '65 GT350s were huge. I have a Bluedot on my spare, and it's probably pretty close to a modern size 205/70/15, or maybe even closer to a 75 aspect ratio. So given you're running 14" wheels, an 80 ratio would probably be about right. Will it fit? It really depends on how much your car is lowered. On my '65, I wouldn't want to go any taller than my 60s in front due to fender clearance, but my tires are 215mm-wide on the 15" '65 Cragars, and have my front end dropped more than what was original.

Another problem is tire availability in 14" sizes. There are 75 and 80s available, but I'm not aware of any tire made in that size that would look good on a vintage Mustang...well, except for non-radials like 14" bias-ply reproduction Goodyears available at places like Universal Tire. The Avon CR6ZZ is a great-looking, great-performing, and by far the most "period-correct" looking radial imo, but it's not available in the size you're looking for.

So if you want to have a vintage appearance and keep your 14" wheels, I'm not aware of any other option other than going with vintage reproduction Goodyears. Then you could get a look somewhat close to the '66s...although personally I wouldn't want to pay that much for tires, on a driven car, that don't perform well by today's standards.

You should be able to run 215 with out a problem. That will also make it a bit taller.

Here's a tire chart that will keep you safe.

Mustang Wheel and Tyre Chart

I'm running 205/70R14's with the lowered control arms, and no clearance problems at all. You could get repro Goodyear Bluedot 7.75x15's, but they actually aren't very good compared to ordinary modern steel radials.

The original 7.75x15's were chosen because it's the largest tire of the period that would fit. If they had been offered a 205/70R14 tire, they'd have used it.

This is a remarkably original 65 GT 350, right down to the tires. The rear nameplate has never even been straightened, having been installed a little crooked.
1965 Shelby GT350 - Mustang Monthly Magazine

Ah, I saw that GT350 at the 2007 MCA show in Springfield, IL...it's originality is impressive!