Goodyear and Firestone were both suppliers to all of the plants. If you have an original spare, that will tell you more than I can.
Tell me the build date of the car and I can tell you what kind of Goodyear would be correct. I can also help you get the best price out there for the Goodyears.
Sorry, I reread the first post. I would say that the F70-14 Polyglas RWL No size would be the correct tire. Here is a link to the photo of the tire I am talking about
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Polyglas RWL no size