If you keep 18/19" with the stock dimensions then it will look the same. There are several close up wheel pics on the net. I don't see much reason to change the tire dimensions. On the e46 M3's the tires were too narrow and many went with wider rubber and a lower aspect ratio but this did create more gap. The e92 M3 has wider rubber.
I plan on going with 10" rears so I will go with 275/35/19 vs 265/35/19 stock. If your not going with 20" then you should be fine if you like stock look. Personnaly I hate the stock gap so no EDC for me. I will put coilovers on with about 1" drop for better stance. If you ordered EDC your pretty much stuck with the gap (new springs are not an option, IMHO).
2009 E92 M3 | Alpine White | Black Novillo Leather | CF trim | M-DCT | Heated Seats| PDC | iPOD
Modifications| KW v3 | 19" BBS LM Champion Edition |Matte Grill |Clear Bra |50% tint | Painted Reflectors