Yup, liquid mask is your best bet. I use it all the time to paint stuff like two-tone dashboards in JGTC cars, intricate headlight assembles, and so on.
Spray your wheel white, let it dry, apply the liquid mask over white with a brush, let it dry, paint your silver, voila!
I use the Microscale stuff, and I swear by it. I have limited success with Silly Putty, as I can never seem to get a clean finished line.
Yay, first post.
