My first 370 had the silver wheels. Despite the lack of a code, they are much easier to match than the dark wheels. You should be fine. It's the dark wheels that are very difficult to properly match.
This is my car from the side on. You'll see that the front wheel, which has been refurbished, is slightly darker than the rear. Fortunately, in the flesh it's very difficult to see the difference, especially because these wheels look different shades at different angles anyway. The picture makes it look worse than it looks in person. At some stage, I'll probably get them both redone so they match exactly.
This is a pre-refurb picture and you'll see that the angle makes the front wheel look darker even though it's exactly the same colour.