the winter tire thing is easy. get your hands on the BMW winter tire flyer, they even state that around 45F and below grip is drastically reduced with no season tires.

or of course, you could believe those that say they hardly make a difference, yet advise you away from spending money to buy the good ones. two thoughts on this, you get what you pay for, and I am not rich enough to buy the cheap stuff....

oh and the point about being in Canada, we get 3 days of snow a year where i live. I would never subject my family to anything less than good winter tires during the cooler months. want to save money? buy used tires cheap on craigslist for the rest of the year... oh, and buy purchasing a second set of tires you can run both other sets longer and save money too...

ignorance is bliss!