Indian Studded tires are only illegal in Ontario for some very dumb reasons
I stud my winter tires since 98 and wouldn't consider anything else for winter driving
Studs da best!
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The designer of a winter tire is faced with major hurdles to overcome. First, the tire must operate successfully over a very wide temperature range in winter (-40°F to + 50°F or more). It must also provide adequate friction on every surface, including wet and dry pavement, ice (wet and dry), slush, deep powder snow, thick wet snow, and various combinations of all of these. If the surface was always icy with some moisture, then a soft and sticky rubber compound combined with a tread design with relatively small grooves for maximum rubber surface area and very large numbers of sipes in the tread blocks would be fine (the so called "ice radial").
However, on roads covered with ice and deep slush, the smaller grooves would not be able to drain the slush out of the contact patch fast enough at high speeds and the tires would hydroplane. In deep snow, large grooves trap and compress the snow (like a very hard snow ball) and much of the grip is provided by the shear forces developed in the tightly compressed snow. So the "ice radial" will not perform so well in these conditions.
Similarly, a block type tread that provides superior grip in deep snow and slush will not have as much rubber and so many sipes in contact with sheet ice, and thus will not perform as well on icy roads or hard packed snow.
The Role of Studs
So where does that leave tire studs? The answer is simple: studs are there to provide additional grip on ice and hard packed snow that becomes like ice. If you rarely if ever drive on ice, then you do not need studs. However, because studs provide extra friction by biting into icy surfaces, the tread design can be slanted more toward optimizing performance in deep slush and snow.
Similarly, because some of the grip on icy conditions is taken care of by the studs, the rubber compound can be made harder to provide significantly longer tread life. In other words, by using studs, the designer can produce
a tire that can cope with a wider range of driving conditions, such as ice, slush, and deep or hard packed snow, and still provide longer tread life as an added bonus