i drive in 3 or 4 in of snow with snow tires and stock suspension and have no problems.. dont think you need chains unless you are going somewhere very extreme... what are you planning to do with your m3 that requires chains?
Current: 2013 F10 M5 & 2013 GLK350
997.1 GT3RS (gone)
2009 WRX STI (gone)
e92 M3 (gone)