A buddy has a set of FC rims on his '69 convertible car. We were looking at the rims today and he asked me about a mark that is present on all 4 rims. It looks like someone just struck an arc with a MIG gun on them. Like a real small BB. Anyone have any idea what this is? It looks factory.

It is factory - that welded "BB" identifies the high point for radial runout of the wheel, and it was originally aligned with the marked low point of radial runout on the tire when the car was built, to minimize what we called "smooth road shake" in those days. Has nothing to do with balance - you can balance a square wheel/tire perfectly, but it won't roll very well. :D

Thanks, John. I was worried I wouldn't get any replies without a picture. I know my buddy has had several people ask him about them, and he didn't have an answer. He thought maybe I would, but I was stumped. TC comes through again! Thanks!!