I have no problems with rear drive and winter performance tires (PA4s) in my M235i 6 speed.
What you need most of the time in Boston is a tire that works great in cold and wet conditions like a winter performance tire. The difference to summer tires is small so I get to enjoy my car all year round - that matters most to me. The few times we get really heavy snow is limited and if it is bad nobody drives anyway - and my office is closed
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Only getting up my steep drive way has been an issue a few times. But that was before I got the LSD installed! With the limited slip it has been nothing but joy. I drive frequently through Maine into New Brunswick, Canada and have no problems. Perhaps putting on 17 inch tires to handle potholes better is all I could improve.
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[FONT="Arial"] M235i 6 speed, MGM. Wavetrac LSD with altered final drive ratio, MPE, MPK Airbox, side skirts, diffuser, Dinan springs, LCAs.