The silver match that you can get off the shelf is Dupli-Color T229 Silver. I went to a paint shop for the charcoal, and supplied the factory paint color #. DDL32947 Charcoal Gray is the PPG equivalent I was given. This is a dark color and I haven't decided if I'm going to use it.

I have a pic of a T/A with the factory wheels. It's has the lighter charcoal colored centers. Many say this is the correct color. Both sets of rallys I have were repainted at some point. Both sets have the darker charcoal centers.