Fuchsfelge states:
Front:
7J x 16, ET23.3 | 5.60 kg | € 549,-*
tyre size: 205/55ZR16
Rear:
8J x 16, ET10.6 | 5.85 kg | € 549,-*
tyre size: 225/50ZR16
9J x 16, ET15 | 6.00 kg | € 549,-*
tyre size: 245/45ZR16
https://www.fuchsfelgeusa.com/pdffiles/G-Modell/G-Modell.pdf
I run what the sizes recommended, currently a set of Direzza ZIII and RE-71R (discontinued).
With that said, I know people who run 225/50 on 7" and 245/45 on 8". Other's will chime in with more personal experience, I'm sure.