Prismatic Speedway Grey
Duplicolor Charcoal Gray Metallic for the center caps, also clear coated them
I also tried Duplicolor Magnetic Gray Metallic (BTY1619) and it was also pretty close. And honestly I don't know that I could tell a difference between the two duplicolor colors after spraying them on the caps.
Black lug nuts
The speedway grey requires a clear topcoat. The center caps don't match exactly, they are a hair darker and don't have as much metallic flakes as the powder coating. The color swatch I got from Prismatic is also a hair darker than the wheels themselves. Total Cost - about $700. I'm pleased with how it turned out. Deciding on the color was hard.
Acid Opulence 3 sitting on the rear tire.
Git 'er done.