Firstly, i'm a licenced automotive tech in vancouver bc. been working for about 7 years now. I've had 3 years experience working at a tire shop and the other 4 as a manager at a general repair shop.


Here's some history on the "All season" tire.

Long time ago, some Joe Blow tested a SUMMER RADIAL tire VS. a WINTER BIAS tire and realized that the radial performed better. Therefore, he said: "ALL SEASON"
That's where it the term "ALL SEASON" came from.

NOW, as you know, in really bad snow conditions, All Seasons, or AS, SUCK! Therefore, we've got WINTER tires. Winter tires have tiny little squiggles in them called "SIPES" What sipes do is open and close so that it can grip the road when your drive, either straight or turning or stopping. SIPES GIVE YOU TRACTION. They almost act like having studs in your tire. The more sipes you have the better traction you'll have in the rain AND in the snow.

Summer tire
-None to VERY limited sipes
-Soft compound, therefore, wears quickly
-$$$
-Usually noisey near the end of it's life


All Season Tire
-little bit of sipes
-hard compound, therefore, wears relatively slowly
-$
-Usually quieter


Snow/Winter Tire
-LOTS of sipes (#2 on image)
-Soft compound, SILICA BASED, but lasts about the same TIME, not mileage, as all
season.
-Noisey all the time
-$$


The other difference between AS and Snow/Winter tires, ST, is that they are made of a totally different compound. The WT uses a SILICA based rubber. All Season tires operate the best ABOVE +7 degrees Celcius. Snow Tires operate best BELOW +7 degrees Celcius. When an AS tire is being used in a climate where it's below 7 degrees, it becomes rock hard and useless because it don't conform the to road and therefore, "bounces" instead of grips the road. On the other hand, if a ST is being used above 7 degrees, it literally starts to melt! It doesn't matter what kind of driving or surface, it depends on TEMPERATURE. Rule of thumb, when the temperature is consistantly in the single digits, go to WT.

Also AS tires will also have deep grooves or channels.

These help to funnel out water so that it's good in...well the rain. In a snow tire, the funnels/channels/groves funnel out the slush. (#1 in pic)




All season tires are meant to give you MODERATE traction in ALL conditions. But, Summer tires are better in the summer and Winter tires are obviously better in the winter. An All Season is a compromise. They give you DECENT traction all year round, but SUCK if you drive hard and SUCK if you drive in the snow. (obviously it also depends on your driving style and vehicle too)

Anyway, hope this help, if you've got any questions, feel free to ask.