jooaa's comment is pretty accurate in my experience, they usually do a good job on the main thoroughfares.

I wouldn't necessarily presume that you'll be dealing with much snow in the road, some years you'll get a bunch of snow, some years you'll barely get any.

I still feel that narrow road tires work just fine for most Boston snow days, although you will slide around a bit... if you don't have to deal with crossing any trolley tracks it usually isn't too big a deal.