Denny, I get that Black from many old wheels which have lost their original coating. Mostly on the old tractors I have which sit out in the sun more than anything else or at least did before I bought them.
I was laughing when I read what you said cause my niece is down here and was driving one of my Ford 8N's and her hands were black when she got off the thing.
I think once the coating is gone the material the wheel is made of just gives up it's substance to your hands.
Just get yourself some black driving gloves and don't rub your face when your driving. lol
Dan

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