An "off the shelf" product that matches the OEM (or is even close) does not exist at this time. Others, and there are threads on the BB about this, have chosen to repaint their set of wheels. (I had the wheels for my series 3 Spider powdercoated by a local wheel shop.) What you may be able to do, is take your wheel to a shop that specializes in fixing and re-finishing wheels, and have them (or their supplier) computer match the color. This is custom work, so for the amount of paint that you will get its is expensive, but it's a lot cheaper than having them re-do all your wheels. The problem may be that they may not be interested in doing this...
Best regards,
Best regards,