The best option is to get a used set of 17" wheels, with mounted winter tires. Swap them twice a year. Second choice is to just buy four winter tires, and use one set of rims. 17" aren't as difficult to swap as the lower profile tires.

It isn't just the snow that matters, icy roads aren't so good on MXV4s either. They are a good all season, but not a good winter tire.

If you do want to get chains, any narrow chain (cable chains, or similar) will work. Rear wheels only, which means that they won't help much for steering or braking, but they will help you go.

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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