You need to provide the offsets. The offsets will determine how far inboard/outboard the face of the wheel will sit relative to the fender. Honestly, there's no one perfect combination. You should search intensively and you'll find the information you require.
If you already have the wheels on the car and are looking for spacers, then you need to measure the gap between the wheel and the fender and that will tell you what spacers to get (assuming you live some room left over too).
2006 M3 ZCP. Interlagos Blue on Dove Grey. 6 speed manual.
Eibach Pro-Kit / Koni externally adjustable F&R shocks / DDM Aluminum Pedals / BMW Performance Short Shift Kit / Clutch Delay Valve (CDV) removed / Painted reflectors / Stealth bulbs / Turner 15mm/10mm front/rear spacers.