I think you're doing it backwards, considering the steering wheel and headliner in determining which wheels to get.

IMO you should start from the premise that you need winter wheels, whether your summer wheels are 19" or 20". Buying an expensive fully optioned awd vehicle in a place that gets real winters, and running it on summer performance tires, just doesn't make sense.

If you don't like the look of fender flares with winter wheels, then perhaps that influences your decision whether or not to get the package that has fender flares.

Once you have the right size wheels on there for all 12 months of the year, the rest will fall in to place.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue