All stock '65+ Corvair coupe and sedan wheels were 13x5.5".
Any SCCA D-Production raced Yenko Stinger was required to run no larger than a 13x7", when competing from '66 thru '72. For 1973 the class became GT3 and thus allowed the pulled out fenders and larger wheels and tires. The only wheels that Yenko sold out of his catalog, were 13x7 double center, steel wheels. They were 2 for $70. :-)
The only larger Corvair GM installed wheels, came on the Corvan, Greenbrier, and Loadside & Rampside trucks. These were 14" steel wheels.
As far as aftermarket wheels, some people have put 16-17" wheels on their corvairs. I'll see if I can find any info. for you as to what fits without alot of modifications.
Here's a couple of pics of my car with the original Yenko Race wheels on it.
The pics. are at Gary Aubes great Corvair site.
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Rick