I received my Silver on Black background 3DCarstickers, and applied them to my titanium gunmental Rial spare center caps from Tire Rack. They look fantastic. As Peter_M experienced, it is difficult to apply them to the silver Rial center caps, because those already include an embossed metal dome applique. The spare titanium caps are different, with a much lower profile, and no metal dome. The 60mm diameter 3DCarSticker fits perfectly. I also tried several different flat and blank 60mm caps off of eBay, but none of them fit to my satisfaction...some were too tight, and others rattled.
As mentioned above, the silver is more a light grey with a slight optical reflection gradient, but it looks good on the T. White or Red would look great also.
Apologies for the low-quality iPhone pics in low light, but here is what they look like:
If you want to order this configuration, here are the links:
Custom design center cap stickers ― Online shop 3D wheel center caps
Specify that you want 60mm diameter stickers, using the NEW Tesla logo with the thicker T bar on top, silver (or white or red) T on a black background. Cost is 15.99 + $3 shipping, and it takes two full weeks to arrive from the Ukraine.
Order the spare set of titanium Rial caps from TireRack, click on the Optional Hardware tab, the caps are $6 each. The description says "Rial titanium center cap - 60mm diameter (Wheel Original)", but they are NOT the same silver metal embossed caps that come installed on the wheels:
http://www.tirerack.com/wheels/WheelCloseUpServlet?target=runWheelSearch&initialPartNumber=LU85932T725TG&wheelMake=Rial&wheelModel=Lugano&wheelFinish=Titanium+Gunmetal&showRear=no&autoMake=Tesla&autoModel=Model+S&autoYear=2012&autoModClar=&filterFinish=All&filterSize=All&filterBrand=Rial&filterSpecial=false&filterNew=All&filterWeight=All&sort=Brand
So for $50 you have a very nice set of center caps. A little pricey for Winter Wheels, but they do look sharp!