17 inch is the minimal size for the F30 335i(rotor diameter)
You can change the tyres offcourse, but I bought a complete winterset(rims + tyres). It's easier and faster to change. But I guess if(1) you buy only the tyres you're first cheaper off but in the long run(labour) I guess not...(2)
I have 19"401 summer wheels and I bought a 18"397 set Continental Wintercontact. They don't come cheap(complete € 2300 but I got a very big discount) If you are going to buy 17 or other inch you're cheaper off offcourse...
Not OEM is cheaper...but the one tyrebrand is better than the other. Continental and Pirelli are winterkings atm in EU afaik.
Last edited by Robin_NL; 11-05-2012 at 08:09 AM.