Depending on how often your trips are renting a dedicated 4x4 may be the better option to protect your 535i on such trips and from other drivers. If you get reward point or some sort of payback it may be the better part of valor. Otherwise a dedicated set of snows can make all the difference man. I had a set on my e92 M3 and did well in light precip I encountered in the greater NE in 2008-2009!
'14 F06 650xi Gran Coupe (Carbon Black Mettalic)- Daily Driver
'12 F10 550i (Dinan S3 Car) - Gone
'10 e71 X6 35iDrive SAV (Space Gray) - Gone
'08 e92 M3 coupe (Sparkling Graphite) -Gone
'06 e85 Z4 M Roadster (Black Metallic) -Gone