Take a look at this thread:
I recommend 275/30/19 in the front - but you will need to remove the camber pins and add negative camber for them to look right.
Who sold you et8 rear wheels? That offset seriously limits your tire options. I don't know what tire size will work without rubbing... I guess you could try 275/30 or 275/35. No matter what you do that wheel width / offset will look ridiculous.
'04 E46 M3 - Jet Black - Sold
'08 E90 M3 - Alpine White - Sold
'13 E92 M3 - Silverstone II - Sold
'13 E92 M3 - Alpine White - 1 Option (DCT), Ohlins TTX, AP Racing, Cobra Seats, Akrapovic GT4, BBS E88, Volk TE37, M3 GTS - Steering Wheel, Aero, 1/2 Cage, Seat Delete