Those 270M wheels are listed as winter wheels for both the M3 and 1M on Felgenkatalog:
http://felgenkatalog.auto-treff.com/ (I can't figure out how to link directly to the wheel's page, but you can find them on there if you look).
Interesting, I didn't realize that BMW offered square wheel sets specifically for winter use. Makes sense, of course - just haven't seen them before.