I got my spitfire back from my buddy in the city. And when I originally put the thick bricks on it a few months ago, I got grease marks on the side of the tire when I put it together well now that its back Im going to be tearing it down and flipping the front sprocket and I wanted to clean up the tires while I had it torn down. does anyone have something special they use on their cream colored tires to clean them?