going to 50 series tires on the '88GT

[Unit 5302]

If you're going to use a lower aspect ratio tire, look for a 245/55 R15. I'm not sure why you want to use the turbines when you can usually find a whole set of rims/tires for under $400 with a little searching.

It gets a whole lot easier if you're willing to spend a few hours doing a 5 lug conversion.

Then you can start shopping for 94+ Mustang wheels and tires. Last time I checked, the Pony wheels were ridiculously expensive for what they are.