Yes they are bare aluminum that are mirror polished by the wheel manufacturer.

I was able to clean up the flat sections tonight by wetsanding it with 2000 grit. Then I cleaned the wheels thoroughly with soap and water. Then I polished the flat sections with Mothers Mag and Aluminum polish with a Mothers Powercone. The results are much better than with the buffer wheels alone. I'll use the buffer for the curved portions and polish the other wheels by hand and with the Powercone.

Ill take some pictures tomorrow. Here is the link to the process that I followed: How to:Polish Aluminum Wheels | S10Forum.com