I would have answered with "Mac" and been in error after Googling.
From what I read, those are early Azusa wheels. They made the McCulloch wheels as well, but the bolts were recessed, not protruding with that ridge. Check kart forums- Removing that raised area and counterboring for bolts is part of the McCulloch conversion. Of course yours would be fronts, since rears are splined for a key way. These might bring in some good money from a vintage karter needing to restore a Mac. Dave-