I have 215/50R17 Dunlop Graspic-2 snows on 17" steel rims on my MS6. I ran them all last winter through all sorts of snow, slush, and ice and had no problems. The only thing I didn't like was the ride of the Graspic-2 on dry pavement compared to the Toyo Observe G2 I had on my MSP.
I have 205/55R16 with Firestone Winterforce M+S on 16" steel rims on my MS3. I just picked up this setup for the wife this week. No snow yet, so I can't comment on winter performance yet, but the initial ride again pales in comparison to the Toyo Observe G2, but at least is better than the Graspic-2. They are also a higher speed rating. I imagine that if you were looking to save some cash, you could put this same setup on the MS6 since the calipers and rotors are the same between cars. The clearance is close, but there is room there and I have not had any problems on the wife's car.
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