RS4 B8 rotor wheel sizings

[Lopseychops]

Apologies if this has been covered already,

I am looking at replacing the Vossen’s that I’m currently running on my 2015 RS4 B8 with the standard factory rotors (running Michelin Pilot Sport 4S - 265/30 R20). There appear to be a number available on Ebay, but I’m baffled by the offset numbers, measurement jargon etc. Can anyone please point me in the right direction as to what I should be looking out for?

Thanks!

Mark.