Aftermarket tires & rims

I have a 2015 RS5. I’m looking to go aftermarket & have done a lot of homework on this. What is the stock rim size & width and how big/wide can one go aftermarket? (obviously I’ll be staying in the 20" realm)

Go 20x10 all around. Best setup out there.

Stock rotors 20x9 et26
I’m running 20x10.5 et35
2014 RS5

Have pics of yours by chance?