I thought many folks here might find this to be a big help... From the Toronto Star 'Wheels' section (Written by Tire Guru John Mahler), Feb 16th, 2008...
"Now, some readers rightly ask, well, what's the difference between snow tires and winter tires? Good question.
For the longest time, there were very few standards in the tire industry. Any company could label any tire whatever it wanted and they did. The "M&S" on a sidewall meant zilch. And it still means zilch.
Technically, if a tire has any groove, it can be marked M&S. That means you could take a Formula 1 rain tire and put M&S on it because it has grooves. So the consumer should ignore all M&S signage.
Early snow tires carried this M&S marking, but competition actually made the companies create tires that did work in snow.
Snow traction depends on several things: rubber flexibility, lots of biting edges and wide grooves. So that's what snow tires looked like: big chunky blocks with square edges and wide grooves all made out of rubber compounds that stayed soft in below freezing temperatures.
These snow tires had decent snow traction, but their Achilles heel was pavement. But square-edged blocks surrounded by wide grooves tend to squirm a lot. So driving down the highway, the tires wandered. Under panic braking, they felt unstable.
Since tread squirm causes heat and heat causes tire degradation, they wore quickly. And last, they were noisy.
Over time this basic model of the snow tire was improved so noise got less, squirm was reduced, wear improved and traction was not diminished.
Tire companies started using more complex rubber mixtures that had less squirm and through computer modelling, found that the tread blocks did not have to be big, square, ugly ridges.
The tire engineers started to refer to the best of these as "winter tires," to help differentiate them from their noisy, squirmy relatives. The winter tires were dramatically better on pavement than the snow tires.
Then worldwide standards started to be adopted. Transport Canada bought into this and so the new winter tire standard was set. Any tire that passes, gets to have the winter tire logo: a snowflake inside a mountain peak, on the side wall.
Another upside of standards was it inspired the tire engineers to make the best of the worst conditions. Bridgestone came up with the multi-cell compound Blizzak, an amazing tire on ice, Yokohama upped the ante with their IG-10, while other companies such as Goodyear and Toyo added grit into the rubber mixture. Michelin, as usual, went its own way and produced the X-Ice, a snow and ice tire.
Of course all this research and technology has improved snow tires, too. So with a snow tire, you still get chunky tread, a bit less stability on the highway and more noise, but you do get snow traction.
With a winter tire, you get quieter ride, very little squirm, less noise than some all-season tires, good pavement ride and grip, long wear characteristics, and – last but not least – good ice and snow traction.
Practical examples from real life: in the Bridgestone Firestone family, the Bridgestone Blizzak is the winter tire, the Firestone Winter Force is the snowtire; in the Michelin/BFG/Uniroyal family, the Michelin X-Ice is the winter tire, and the BFGoodrich Winter Slalom is a snowtire; in the Pirelli world, the Snowsport is a winter tire and the Winter Carving is a snow tire.
So to legislate or not to legislate? Several readers pointed out my omission of school buses in my list of vehicles that should be mandated to have winter tires. Good idea. Car rental companies definitely should be included in a law.
Studs, I'm less crazy about. On ice and hard-packed snow, the extra grip is amazing. On pavement, where most of driving is done, they can sometimes make stopping more dangerous and they do eat up asphalt. In Southern Ontario, we have so little pavement left to eat. All the 400-series of highways look like ads for "instant pothole patch."
Instead of making winter tires mandatory, why doesn't the provincial government allow you to write off the cost over four years on your tax return. A carrot is always better than a stick, plus it would help stimulate our retail sales in Ontario.
But what the hey, what do I know?
I do know there are some tires out there that I like to call all-weather (I'm leaving the "season" word to Vivaldi and Glazunov).
These tires can run in the snow and enjoy a day at the beach in July ....but Mr. Editor is tapping on my shoulder. It seems I'm writing a column not a book. So we'll talk about those another day".
