I live in Minnesota. I've seen lots of people recommend changing to winter tires in the winter. However, what doesn't make sense to me is that the roads are plowed very well here. 90% of my driving in the winter is either on dry or liquid-wet pavement; it is rare when I drive in the snow or ice. So I should get winter tires for conditions that are only in effect 10% of the time? Why not then keep the winter tires on year-round?
As I said before, it's a trade-off: All weather tires vs winter tires
So I should get winter tires for conditions that are only in effect 10% of the time?
It depends: how bad is that 10%? Is it the difference between well-plowed and deep snow with a slush garnish? Are you trying to improve the handling or are you worried that you'll:
- get stuck
- not be able to get to the top of a critical hill
- not be able to stop at the bottom of a critical hill
- not be able to make that icy turning offramp up ahead
I live in Rhode Island with all-season tires and our snows are generally minimal or manageable, well-plowed (especially after I've finished shoveling my driveway) and I avoid driving when I'm worried about other drivers.
Even so, I still wish I had dedicated snow tires for exactly that 10% when everything goes wrong and all the margins of error become much tighter.
Why not then keep the winter tires on year-round?
Winter tires will give poor performance on dry hot roads when considering handling, top speed and road noise. They're wasted in warm weather unless you decide to try rallying or rallycross.
EDIT: Holy cow. The winter of 2014-2015 has been crazy even in Rhode Island! This year, I bought nice winter performance tires and I'm so much happier. The performance envelope is much wider, giving me a lot more room to avoid the crazies who shouldn't be driving even on a dry summer day, much less in the snow! I'll be getting new summer wheels and tires in the spring and switching back and forth from now on!
For the part of the question of why not just leave winter tires on all year, see Why should winter tires not be used at summer? (essentially, they aren't made to handle summer conditions)
It isn't purely about surface conditions, although that is a big portion of it. The compounds that winter tires are made out of are designed for the lower temperature ranges.
Its the simple jack of all trades master or none statement.
Winter tires excel in cold weather, will fail in summer.
Summer tires excel in summer and will fail in winter.
All-Season tires will work in both, but cannot match the performance of the specific season tire.
First of all, winter tires doesn't mean tires designed for ice and snow, these are tires designed for winter time, which mean mainly low temperatures. When the outside temperature is going below 7 degree celsius you start to get poor performance from summer compound. As an example, breaking distance stretches significantly,
The only all-season tire with winter compound on the market is Nokian Weatherproof. But winter compound for all-season tires has its drawbacks.
Because winter tires compound not only gives terrible performance in summer time, but it just degrade fast and permanently when used in summer conditions.
That's why is a bad idea to use winter tires all year round, during summer they just literally break down chemically.
If selecting all-weather tires, please note that there are many different kinds of all-weather tires optimized for different conditions. For example, mine (Michelin Latitude Tour HP) are advertised as all-weather tires. Well, when driving on extremely light snow, I noticed that the traction control light of my car flashed during very light braking. In the same conditions with true studded winter tires, I would never have had the light flashing.
These "all-weather tires" are my summer tires. I think they probably are optimized for summer, which means they can't handle winter. There may be different optimizations for all-weather tires too, with some being better in winter -- and worse in summer.
So, the answer to the question whether you need proper winter tires on well plowed roads: if there's even a thin film of snow, yes, you do.