|Some of you guys want to keep the wheels as inset as possible whereas others prefer a little poke.
My recommendation would be to go on willtheyfit.com and play around with the calculator to figure it out for yourself. Stock is:
Front: 16” x 7.5” 45mm Offset
Rear: 16” x 8.5” 35mm Offset
My setup, which is probably a bit aggressive but still fit perfectly fine without having to roll fenders is:
Front: 18 x9.5 +28
Rear: 18x 9.5 + 38
The rears are absolutely perfect, I could maybe go out another 5mm but then I might have to roll fenders. I'd say 18x9.5 +35 is a perfect size and offset for the rear. Mind you this is a factory TT so not a NA to TT swap, they can have more positive offset because the lack of HICAS.
For the fronts I have the same wheels as in the back but I put a 10mm spacer to clear the strut arm/knuckle. Dunno if I would have rubbed on the inside, Barry on here is running the same size (18x9.5) but +35 offset I believe and is having no issues. If you took those wheel sizes as your maximum and then played around on willtheyfit.com you should come up with something that makes you happy. There are some people running 18x9.5 +22 up front but they're poking like crazy and most likely rolled fenders. My guess for the fronts with an 8.5 wheel is anywhere between +25 and +45.