From sipes and studs to three-peak mountain snowflakes and ice grip symbols, we decode winter tire lingo
If you’ve spent any amount of time in Canada during months in which snow and untold misery falls from our skies, you likely know (or at least begrudgingly acknowledge) that winter tires are an indispensable piece of added insurance on Canadian highways. Unique rubber compounds and creative tread designs create molecular and mechanical advantages in grip which all-season tires simply can’t match.
Why is a winter tire different than an all-season tire?
The major puzzle pieces which make a winter tire the ideal safety companion for harsh weather are filed under molecular and mechanical. The former refers to the compound of which the rubber is made while the latter refers to the tread pattern. One can be easily seen, the other cannot – but both are equally important.
That molecular part, or rubber compound, is the secret brew of materials which tire companies invest untold amounts of time and money, chasing perfection through new manufacturing technologies and advancements in science. Yes, actual scientists work on the development of those four rubber hoops located at each corner of yer car, mainly in teams creating new rubber formulations.
Winter tires use a rubber compound which is generally softer than what is found in an all-season or summer tire, retaining a skiff of flexibility when ambient temperatures drop to numbers generally associated with the planet Hoth. This helps with grip properties and explains why non-winter tires skid about when temps plummet while winter hoops provide much more control.
Meanwhile, the mechanical part (tread pattern, remember?) is comprised of the entertaining combination of blocks, sipes, and voids – all of which create the best possible surface with which to press into winter’s worst and grab a fistful of traction. We’ll describe the roles of each a bit further down the article.
So what makes a winter tire grippy in cold weather?
Closely examining the tread pattern of a winter tire will reveal hundreds of little zig-zags in the tread blocks – these are called sipes and are a key component of grip. When the tire is pressed into a surface, those sipes open up ever so slightly, creating extra biting surfaces with which to grab a bit of traction in slick or cold conditions. The shape of the tread blocks themselves play a similar role, as do the voids between those blocks. Rubber compounds often include ingredients like silica and the like to add tractive properties, as well.
Further up the food chain, some drivers swear by studded tires, while others swear at them. Studs are designed to bite into ice surfaces and packed snow, similar to crampons worn by adventurers working their way up the side of a frozen waterfall. Modern tires studded from the factory are much quieter than the roaring units of yore, thanks to engineers who have figured out how to permit studs to slightly deflect into the tire when rolled over a hard surface like dry pavement. It’s as close as we’ll get to retractable studs for now.
Does the Three-Peak Mountain Snowflake (3PMSF) badge mean anything?
You bet it does. As an industry standard, a tire needs to pass a specific testing regimen in order to qualify for the symbol, performing at a so-called traction index equal to or greater than 110 compared to the reference tire which is rated at 100 on packed snow. The 3PMSF standard is designed to help ensure shoppers can easily identify tires which provide a higher level of traction in foul winter conditions.
Interestingly, these testing measures evaluate a tire’s acceleration traction solely on medium-packed snow. Alert readers will quickly realize that braking and turning on snow, along with ice traction, are not components of the 3PMSF test. In fact, advancements in tire tech mean that more tires than ever before are permitted to bear the mark; that doesn’t mean the hurdle is any less difficult to clear, just that tire companies have more tools at their disposal to build such capabilities into their tires. This dovetails nicely into our next section.
What is this new Ice Grip symbol found on winter tires?
Tire companies such as Nokian are perpetually chasing product improvements, some of which are such quantum leaps in performance that they demand the notation of a new industry standard. Drivers shopping for a winter tire this season are likely to see reference to the Ice Grip symbol, a fresh measure of traction helping keep cars shiny side up when the weather turns foul.
Think of the Ice Grip symbol as a step beyond the 3PMSF symbol which appeared in 1999. Like the existing standard, it demands that a tire outperform a reference tire – but in this instance it must do so on ice and do so by 18% instead of the 10% leap required to earn the three-peak mountain snowflake. Both the studded Hakkapeliitta 10 and non-studded Hakkapeliitta R5 earn the Ice Grip symbol; the latter has cryo-crystals which act like built in studs but without the metal-on-pavement noise. Installing a tire like one of these Nokians is like levelling up in a video game and easily dispatching the bad guys – except in this case yer easily handling the worst winter can throw at your family out on the open road.
Are winter tires more expensive than other types?
Generally, yes. Thank (or blame) the extra research and development plowed into winter tires to make them grippy in a myriad of bad weather conditions, not to mention the materials used in production are generally sterner stuff than that of a milquetoast all-season tire. Toss in specialized machines to make these things in factories and the inflated (pun intended) prices of a winter tire are explained.
Do I need to change winter tires in the summer? How do I store them?
Yes. Leaving winter tires on during hot weather will cause them to wear very quickly. Why? That same soft rubber compound which permits the tire to grip in cold winter temperatures like cats on cotton blankets will shed quickly when the mercury climbs to summertime levels. Just like you wouldn’t wear those Sorels to the beach, nor would ya run winter tires in the summer. Some garages or dealerships offer storage facilities for a fee, though stacking the things in a dry corner of yer basement is a viable option if you have the space.
Why aren’t you calling them ‘snow’ tires?
Because modern winter tires have valuable traction advantages compared to all-seasons simply when the ambient air temperature is below 7 degrees Celsius. There doesn’t need to be any snow on the ground to take advantage of the traction benefits found in a winter tire; its rubber compounds are useful on cold and dry pavement since it remains very pliable. Put it this way – would you rather traverse a frozen parking lot in Sorel boots or plastic flip flops? Tire experts will tell you the comparison is apt.
Should they be the same size as my regular tires?
That’s the best idea, yes. Mounting a size different than then one with which a car was originally equipped can be a recipe for disaster – the tire could be too wide or too tall, either of which could cause clearance problems which may lead to premature and sudden failure. Try walking on a slippery surface in shoes three sizes too big for your feet if you’d like a real-world example of this phenomenon. Difference is, you’ll fall at walking pace instead of suffering a blowout at highway speeds.
If you are having trouble finding winter tires the same size as yer car’s original equipment size, consult a tire professional for help. It is possible to, for example, install 18-inch winter tires on a vehicle equipped with 20-inch all seasons, but the process requires math in order to find a size which is of equivalent overall height and width. And, of course, new wheels will be required.