My Orig spare 1967dated Model 1968 14 x 6 Coded "XG" rally wheel is Gray on the back side.
I even think the Book By Colvin has a wheel section and some manufacturing drawings that include painting instructions.
So is it fair to say Black primed wheel base color is NOT,,,,,, a all // every time. You guys might be just talking about 69's,,,,,,,??
Jim