Thanks for all the information johnsjmc !
They are probably just painted as the discs are not drilled. As I can't see the Create Album in the Control Panel, you could see my car and the brakes at the following link (although it's hard to see):
http://i.imgur.com/xwWuDEO.jpg
This one may be a bit clearer (not by much)
http://imgur.com/uvhgVvL.jpg