Here is what your looking for, shows partnumbers and sizes, AMG III SL55 wheels for an 07, but will fit all R230. See attached..
Also attached is a longshot worth doing some investigation. This company did some refurb work for me, and it looks like they have just about any wheels made.. They don't advertise, I found their name by accident on a lable, looked them up on the internet, found their phone number, and 2 calls later had a deal to refurbish a set of AMG's. They turned them around in 5 days.
But it looks like they sell refurbed wheels also, it's worth a call...
When you go to their website they look for a business number to get inside for data, but as a guest, just look thru their retail catalog, you need to look carefully for the link that says retail catalog, if nothing else their phone # is on the bottom of the last attachment..just call them
That bottom attachment shows the prices for the 8.5" front wheel, the rear 9.5 inch wheel is also available at the same price..good luck