http://www.realoem.me/Audi/RDW/A8/20...R/4/407/407001
Change the URL where it says 2006 to your model year.
Then look at items 13 and 14 and match the PR code in the right column with two of those on your wheel-well sticker.
There is probably a difference for sports/not sports, but most aftermarket ones seem to be universal/interchangeable anyway.