They are aluminum. Paint thinner and carb cleaner does nothing. Acetone does not even work. Paint stripper works on the asphalt slowly, but not the dark stain. I used repops on my Challenger, and they fit terrible. A-body repops run around $350 for a set, which seems like a lot. I can use a buffing wheel, but am afraid I will snag an edge and destroy it. Still looking for a chemical solution.