The only info I can find is that they are 17" and called style 413. Interestingly, even the BMW F30 brochure doesn't even have a photo of it.
And this:
http://www.realoem.com/bmw/showparts...90&hg=36&fg=15
And then this as a full set: part numbers are different though, so who knows if the two different tires listed are accurate.
http://www.realoem.com/bmw/showparts...15&hg=36&fg=95