Without being in your area, talking to the people in your stores and finding out what they can get or might have we can only tell you that
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those tires right there will fit your car, are avalible, in stock and are the right size (145 R12 are another labling for 145/80 R12), , your other option is to talk to the people who have worked at the tire shops for many years and see what they have hidden away in the back, I've gotten odd tire sizes this way before, you can also call up places that sell NEV's (neighbor hood electric vehicle) and ask if they can get tires in your size because there might be a NEV out there that uses them, seeing as how NEV's tend to use some weird small tires, some of us have spent days calling every tire place we could find to find other odd sizes, for even odder vehicles, 12" tires are not that odd in comparison.