The difference between all seasons and summer tires is not only the tread patterns but more importantly the tire compound. Summer tires are only meant to be driven to a certain temperature. Below that temp, usually around freezing but my experience it is more like 50*f, the rubber becomes hard and lacks it's stickiness. Basically you would be driving on hockey pucks with zero ability to get traction and conform to any road irregularities. All season tires are more forgiving in cold weather and maintain a level of conformity in freezing temps.
Narrow tires operate better on slick roads, snow, ice or rain. This has to do with contact patch, flotation and some physics. (some will argue that wider tires will act as a paddle and float on top of the snow. This is true but a concept more reserved for offroaders in the backwoods cutting fresh trails. Another topic altogether. Now I digress)
If you look at summer tires vs. all seasons, you'll notice the designs are quite different. Summer tires tend to have large solid patches of rubber. Some have water channels running along the circumference, others don't. But very few have summer tires have the almighty siping. This siping helps aid the tire in griping the road during wet weather. In icey weather, they help to grip the ice by squeezing away that thin film of water on top and actually gripping the ice sheet below. It's the water film on top of the ice that's the killer. They also aid in conforming to the irregularities of the road surface.
In snowy weather the siping does the same job. But there is one thing that people don't think about, You want to pack the tire with snow to gain traction not completely slick it out but snow in tires aid in traction. Yes, this is contradictory to the belief of keeping the tread block clean. Think of your tire as a snowball and as you would pack more snow on the snowball to make a snow man, the snow sticks to itself aiding in traction. All of those little sipes and voids in the tread act as snow packing velcro. Go look at dedicated ice/snow tires, you'll get what I mean.
The afore brings me to dedicated winter tires. These tires possess compounds making them ultra flexible in freezing weather. The tires have tons of siping, large and small, and provide a level of winter performance unbeatable by even the all season. Winter tires will simply stop, go and turn far better than any other tire in winter conditions. However, they are incredibly whacky on dry/warm roads tending to be too soft and unstable.
Beware! winter treads will wear quickly if your winters tend to get warm and dry frequently throughout the season. And they can be spooky.
I drove my first winter on the summer Dunlops cause I had too, never again!! First icey sleet we got, I sucked the seat up so far I could taste the fabric. We only get a handful of winter weather per season here so all seasons fit my bill. I went with the Continental Extreme Contact DWS. They are speed rated, m+s rated, quiet and ride well in below freezing temps. The tread has tons of those little sipes and voids for snow packing and ice gripping. Drove in 8 inches of snow without issues. Stop was good, go was good and steering was decent. Ice traction is decent, as well. Your car will plow and bottom out before the tire gives up.
IMO they give a good winter drive without losing too much performance in the dry. These would be a good option for someone needing one tire for year 'round service or someone experiencing winters with a broad range of weather, i.e. warm to frozen.
Hope this wasn't too long winded!
