Need Center Caps for TRMotorsport C1s

[IAmGary]

Got these wheels from TireRack and ordered the TRMotorsports center caps (shipping soon). I'd like BMW center caps to put on them but I'm really not sure what or where to buy. I've seen these wheels on old for sale threads with BMW caps so I know it's possible. Anyone have a recommendation?

The wheels.

Cheers!

[IAmGary]

Just thought I'd update this thread in case anyone else comes here. I bought the center caps for my wheels from TireRack (which arrived same day even though I didn't pay for that!) and was able to measure the ID of the top of the cap.

45mm badges which are available from Amazon should fit perfectly and look like this: http://www.r3vlimited.com/board/showthread.php?t=197068