I have a similar setup--Dinan Stage III suspension on an E90 ZCP, with a set of Turner 12.5mm spacers all-around that I use sometimes. As you know, a lot of factors can determine whether you will get adequate clearance. Obviously my spacers are 2.5mm thinner than yours up front and 0.5mm thicker out back, and the sedan may have slightly different clearance than the coupe, but hopefully some of my info may help (this is all on OEM ZCP wheels):
Stock 245/265 Pirelli PZeros with 12.5/12.5 spacers---consistent rubbing in rear on bumps (PZeros have very square shoulders, so less clearance)
255/275 Blizzak LM60s with 12.5/12.5 spacers--occasional rubbing in rear on big bumps if back end loaded (Blizzaks have more rounded shoulders)
255/275 Michelin Super Sports with 12.5/12.5 spacers--rubbing in rear on big bumps
So, as suggested above, probably the safest bet would be to do stock-size 245/265 Super Sports if you want to still use the spacers, or ditch the spacers and upsize to 255/275 Super Sports. That's what I currently do in the summer--255/275 with no spacers on GTS wheels (just black ZCP wheels) and it looks nice and aggressive, especially with significant neg camber up front. The 255/275 setup is very common on the ZCP wheels. It seems to be the best compromise--not overly stretched on the ZCP wheels like the stock 245/265 setup is, and not oversized for the ZCP wheel width like a 295 would be out back.
IB E90 M3 ZCP returned to BMW FS