Re Snow tires vs all season

I agree with pm_belo, I have an E53 with 19's (summer) and I knew that the 18 all seasons would not work outside of downtown TO. Anywhere else it is worth the investment in snow tires. IMHO all seasosn are "no-season"tires. They are not as good in rain or heat as summer tires and fail miserably if there is more than 5cm of snow. I change in November and March/April - it makes an enormous difference, the initial cost is offset by not having to replace the tires as early and most importantly in safety.