FS-I did some research and this set up will fit the Z4 3.0 post 2010 new body style as well, they are the recommended winter tire, wheel configuration per Tirerack.com as well as the BMW winter tire suggestions. Serious inquires only
Sport Edition Multi spoke 17' wheel Dunlop Winter Sport 3D, Speed rating 93V
Size 17x7.5
Offset-+40mm
Backspacing 5.86
Bolt pattern-5-120
Tire -225/45/17
I used this set up on a 07 Z4 3.0Si for three winters they have less than 5000 miles total. The reason for such low mileage is I have a company car for work related travel.
I traded in the Z4 for my current vehicle a 328i. I am in Grosse Pointe (near Detroit) Great combo, no worries in the snow, great traction, wet, dry, snow/slush and speed rating is a V allowing speeds of 155 mph. Go to Tire Rack and check out the reviews if you like. I would ask $1000.00 OBO for the set seeing as they have very little tread wear, no road rash and have BMW TPMS sensors installed as well.