You can’t get inexpensive tires for those rims
I very much enjoy Auto Restorer and read the magazine from cover to cover as soon as I get it. The recent article on wheels and tires prompted me to write. I have a 1985 Ford Mustang convertible. It’s been a great hobby car for me because parts are so inexpensive and easy to find. With having to put four children through private schools and college, there was never enough money for my hobby so the Mustang came in a distant 5th place.
My problem is that I was given two sets of TRX aluminum rims that were original equipment on some early fox body Mustangs. I really like the look and the car’s stance when they are mounted but new metric tires for these rims are way, way out of my price range. For years I have been trying to research these rims to see if there are less expensive tires or a way to adapt a common size tire to these rims. I’ve been told that since the rims are metric, no American-made tires will fit. Don’t the BMWs, Saabs, Mercedes and other foreign cars have metric sized tires? Can the aluminum rims be machined in some way to accept American-made tires?
I don’t have any good news for you, Brian. Your rims cannot be machined to accept another, more common-size tire. As you’ve already discovered, new Michelin TRX tires sized 220/55VR390, which are the correct size for your Mustang TRX rims, cost over $500 each. Some BMWs, Audis, Peugeots, Citroens, Alfas, and other European cars used the same tires as were originally used on the optional fox body Mustang TRX wheels but that does not in any way solve your problem.
TRX tires were the first mass-produced low-profile, high-performance tires and they were manufactured exclusively by Michelin. While other, lower-cost tires sized for the TRX rims have been made over the years none are currently available and given the relatively weak demand it’s unlikely that anyone is going to make new ones.
So right now the only potential way to get inexpensive tires sized correctly for your metric rims is to find good used ones and that, as I suspect you’ve already discovered, is a very difficult task. And putting price aside for the moment, the used tires that occasionally crop up on Internet auction sites, enthusiast forums, and elsewhere are typically more than 10 years old and I don’t recommend driving on tires that are more than 10 years old.
Given the totality of circumstances, your most sensible course of action at this point is to sell the rims you have and buy new rims that will accept commonly available, lower-cost tires.