Just got a promo email from BMW promoting winter tire and wheel packages. Looks like they are about $1200 higher than Tirerack for the same tires. They are offering either 16" Blizzak LM-25 (2450 on alloys) or the Dunlop Wintersport M3's (1850 on steelies with hubcaps) for the 3 series. Granted,the wheels are undoubtedly better quality but for use in salt and sand..... 
Yikes. For that price, those 16" (style 156) look pretty small on the actual cars IMHO. For $500 more, you can get the (IMHO) nicer 17" (style 159) wheel set.
I negotiated my winter set with the purchase of my car, so I could get another style. If I wanted the 16 inch wheels, I think I'd pick another style or go with tirerack. Of course, this is all personal opinion.....