2017 with Perfromance Pack - What wheels?
 

Just got my new (bright yellow) 2017 BRZ - came with the new performance pack which include Brembo Brakes, Sachs dampers and "special" wheels - 17x7.5 48mm offset. While I am very happy with the handling I'd like to explore the vehicle's limits with some wider sticker rubber. It came with the same 215/45 R17 Michelin HPs the other BRZ's come with. The OEM wheels clear the Brembo calipers by a hair.

Question: without body or suspension modification does anyone have an idea what the biggest rims and rubber I can stuff in there would be and what offset would be required?

Explore limits? As in have some go on track or some canyon runs and you do care also about handling?
Then i suggest first reading this, and then rethink, if "biggest rims and rubber you can stuff in there" is really-really what you want.
If you just want more grip, and car will still be NA, just get rear LCAs, front camber bolts and stock-sized or at most 225 wide tires of better type. MPSS, AD08R and alikes. No need to stuff in "biggest" size-wise .. if you DO care about handling & driving fun, and looks is not in absolute priority to everything.
As sidegain - it's really fun to spend money saved on not needed parts in even more trackdays :)

thanks for the link - handling is what I care about, not looks (unless the look is truly ugly)

thank you Swarb - I did try looking and got a bunch of confusing info and mostly people asking the same thing as me. Perhaps I will just go 225 with better rubber as soon as these Michelin HPs wear out - I have never seen such a tight clearance between these Brembo calipers and a rim on any other vehicle: getting the wrong offset and being stuck with 4 rims I can't use is not something I want to happen and I can't find a local shop in MN (yet) who actually knows what heck they're talking about with this specific vehicle and rims. The dealer knows less about this car than I do - they're no help...

If you are using BBK .. get from manufacturer brake fitment template & use it to check clearance prior purchasing anything. Will save time, nerves & money.

All of that information is valid for previous model year BRZ/FRS but the 2017 BRZ series.Yellow and Performance Package come with a BBK from the factory that a lot of wheels don't clear.

Search for wheels that will fit the 2004 STI. The rotor/caliper on the BBK on those is almost an exact match for the Performance Package BRZs and still has the 5x100 bolt pattern. Anything that fits the 2004 STI will fit our BRZ

thank you sir - will do.