my research has led me to believe that the pilot sport a/s 3's are the best all season option for this car. they will still provide grip when its colder (below 45 or so the super sports lose a lot of grip) while still being more than enough in the winter. here are some nice reviews.
http://www.bmwblog.com/2014/04/07/mi...port-3-review/
http://www.bmwblog.com/2013/01/22/bm...ot-sport-as-3/