No traction system in your car or truck can operate except through your tires. But here in North America, it can be hard, if not impossible, to tell if a tire is safe to use in winter conditions. And that’s what a new Ice Grip symbol aims to fix. Already rolling out on tire sidewalls, it indicates a tire has undergone testing to demonstrate safe levels of traction on bare ice.
I talked to two of the engineers behind the symbol to find out more.
Why do we need a new sidewall stamp? Well, last winter’s record snowfall in Tahoe provided the perfect example. Drivers visiting the area to ski were filmed pirouetting down hills, piling up in multi-car crashes, and generally exhibiting poor behavior. Why? Because every one of the cars filmed struggling was wearing inappropriate tires.
Tahoe indicates a larger problem. Like we explored at the time, existing sidewall symbols, tire categories, and government regulations are colliding to dangerously mislead consumers. Let’s briefly recap some tire terminology:
All-Season: A type of tire drivers understandably assume is safe to use through all four seasons, but is in fact simply the cheapest possible option. All-season tires begin losing grip even on dry pavement as temperatures fall below 45 degrees.
All-Terrain: A type of off-road capable tire that prioritizes on-road safety and efficiency. While an all-terrain may wear sidewall stamps that indicate winter capability, many don’t. And even though many drivers assume all-terrains make a good option for tackling winter conditions, none match the safety provided by a true winter tire.
M+S: Like the topic of this article, a sidewall stamp. This one claims to indicate capability in mud and snow, but is actually obtained through a two-dimensional analysis of the tread pattern indicating a ratio of at least 25 percent void to lug. California regulations refer to tires wearing the M+S stamp as “snow tires,” and allow any all- or four-wheel drive vehicle fitted with them to drive over snowy mountain passes without first fitting chains (you must still carry those). It’s easy to see why drivers assume M+S tires are safe to use in snow, but no test of any kind is required to earn the stamp, and it indicates no designed, intended, or incidental capability in winter weather.
Three Peak Mountain Snowflake: Commonly abbreviated to 3PMSF in North America, or “alpine tire” in Europe, tires which earn this stamp have completed an actual test. The ASTM International F 1805 procedure requires that a tire must demonstrate acceleration traction at least 10 percent superior to that of the Standard Reference Test Tire, which is manufactured for that express purpose by Michelin and has characteristics similar to those of a typical all-season. That test is performed on medium-packed snow only, and while tires wearing the 3PMSF may perform better than that 10 percent baseline, there is no way for consumers to learn that information. As a result, 3PMSF also ends up being effectively meaningless in the real world. A tire wearing it may perform better in winter conditions than a standard all-season, but how much better can vary from that 10 percent minimum, to something that genuinely feels safe and reassuring.
And that’s it. That’s the extent of officialdom surrounding what defines a winter-capable tire in North America. As a result drivers are left to parse consumer reviews, tire maker marketing, and my advice if they want to run a tire that will actually make them safer in winter. A situation that’s far from ideal, even if judged only from the perspective of the number of unread emails in my inbox.
Enter Mikko Liukkula and Jarmo Sunnari, respectively the development manager and global product manager for Finland’s Nokian Tyre.
“People didn’t understand that wet grip and winter grip and snow grip and ice grip were different things,” explains Sunnari. In Europe, there’s actually two categories of winter tires: those designed for central European conditions—where the challenges are rain and slush—and the ones necessary to drive safely in nordic countries. Not only are temperatures far colder in those countries, but roads at northern latitudes remain snow-covered all winter long. Since you can drive on frozen lakes, the amount of drivable terrain is much larger in the wintertime. So, while a 3PMSF tire might be good enough in Luxembourg, that standard isn’t stringent enough for Luleå.
“We tire manufactures realized this dilemma that we have two types of winter tires in Europe,” Sunnari continues. “We have the nordic winter tires with terrific ice grip, and we have central European winter tires with terrific wet performance and high speed performance. And we wanted to have this element somehow visible in the tire labeling, so that the consumers would not be misled by the label and the criteria, and the performance that it shows.”
So, about a decade ago, Sunnari and Liukkula worked with their colleagues at other European tire makers to establish a winter tire working group within the European Tire and Rim Technical Organization, which promotes safety through mutually agreed standards and testing.
“And so we started there, together, to create a test method,” says Liukkula. “We selected some tires and we tested together in various conditions and, little by little, we restricted the conditions and the methodology. I think we did two or three years of testing together. And then we restricted the parameters, the temperatures, the temperature window. For example, for ice and snow, how the tire load conditions should be, how different sizes could be tested, and so on.”
The challenge in establishing a test standard is to eliminate variables while staying relevant to real world conditions. Winter driving is unpredictable. Drivers encounter many different types of snow, for example, and driving along a road through varying altitudes, sun exposure, wind conditions, and human activity vary snow from loose powder to hard pack to bare pavement and back again, constantly. But the most difficult challenge a tire will encounter is ice, which is pretty straightforward for humans to create and control. So, the ETRTO working group decided to focus on icy surfaces.
First published in 2021, the resulting International Organization for Standardization (ISO) 19447 test specifies a course that, “shall be flat, smooth, polished ice and watered at least 1 hour before testing.” Air temperatures measured 3.3 feet above the surface must be between 5 and 39 degrees Fahrenheit, while the surface of the ice itself must be between 5 and 23 degrees. The standard also instructs that weather conditions like precipitation, blowing snow, and direct sunlight must be avoided. Brand new tires are used, but each is broken in for 62 miles on bare pavement before initial testing, and 3 to 6 miles between each test run. Michelin’s Standard Reference Test Tire is used as the control, and must be the same size and load rating as that which comes standard on the test vehicle, and as the tire being evaluated, and both must be inflated to pressures specified by the vehicle manufacturer. Test runs are then conducted while braking from 15.5 miles per hour to a dead stop.
I asked Sunnari why the braking test was chosen rather than, or in addition to, acceleration or lateral grip. “What we decided in the very beginning of the development of this method was that we need the simplest possible way to segregate the tires upon the ice grip,” he explains. “So the easiest way was ice braking. And that is also creating the most safety. Acceleration is of course important from a mobility point of view, but it is not as important from the safety point of view. And when you have good ice braking properties on the tire, you probably also have good acceleration and good side grip.”
“The short answer is we use the ice braking test because it’s the simplest way,” continues Liukkula. He explains that Nokian uses a 2,300-foot long tent to cover its test course to eliminate environmental variables, and that the test must also be repeated three times on three subsequent days, with the control tire running both before and after the test tire. All runs are averaged at the end, and to earn the ice grip symbol, a tire must demonstrate an average stopping distance at least 18 percent shorter than the reference tire.
Is an 18 percent difference at 15 MPH really a significant advantage? “The relative performance between the tires is not changing if you change the starting speed,” says Liukkula, going on to say that you can continue to extrapolate that same percentage difference as speeds increase.
That’s something demonstrated in this video Nokian put together. 40 kilometers per hour is just about 25 miles per hour, and we can easily see here that the difference between an all-season (what Nokian labels a summer tire), and a winter tire wearing the ice grip symbol (nordic non-studded) is a full 197 feet. The ice grip symbol tire also stops 65 feet shorter than a 3PMSF tire (what Nokian labels a Central European winter tire). That could be life or death, even at such a low speed. Or the difference between a ski day, and a very expensive tow to a body shop.
What about the performance of the studded tire? Nordic countries don’t plow their roads clear of snow like we do in North America. Studs wear to the point of uselessness in as little as 1,000 miles when driven on bare pavement. While studded tires may offer some benefits over standard winter tires when new, the studs wear out so rapidly in North American conditions that they aren’t a great choice here.
Nokian currently sells one tire without studs in North America fitted with the ice grip symbol—the Hakkapeliitta R5. But more should be on the way, both from Nokian and other brands. “I’m quite sure they will come in the very close future,” says Sunnari. “Probably the next products they will launch they will also have the ice grip mark. We have developed this method together with Continental, Michelin, Pirelli, and Bridgestone.”
One of the great tragedies associated with winter tires is that, even if you and I go through all the expense and effort of swapping onto them each season, we’re still only as safe as the drivers around us. Without incentives like reduced insurance rates or government mandates, there’s no way to improve that situation. But that’s actually the most exciting thing about the ice grip symbol. Since it finally gives us a standardized ability to define true winter capability beyond 3PMSF, it opens the door to official recognition of what a true winter tire is, and the benefits that tire can bring not just to individual consumers, but to all road users in areas that experience winter weather. Right now, winters are only required in a handful of European countries, some areas of Japan, and Quebec. A little sidewall stamp with three icicles hanging from the peak of a mountain could be what finally changes that.
How To Use Winter Tires
Since winter tires are such a novel concept to American drivers, I think it’s a good idea to include some basics in any article about them. I’ll keep this as brief as possible, linking to more information.
- This article provides a more detailed explanation of why studs aren’t applicable to North American roads.
- This article explains why all-wheel drive is not a replacement for winter tires.
- This article includes many fun examples of people driving badly on the wrong tires, as well as an explanation of why you don’t want to rely on chains.
- This article contains my current recommendations for winter tires for 4x4s, trucks, and crossovers.
- Here’s an article about all-terrain tires.
- How do you afford winter tires? In the five years that most car purchasers own their vehicle, you’ll need two sets of tires anyways. Moving that purchase up, to buy a set of winters, doesn’t add any money to that total, while potentially saving you all the costs associated with a crash.
- Winter tires are safe to use in warmer weather, but wear out quickly in temperatures above 45 degrees. Either pay a tire shop to remove and store your summer tires every October, then refit them and store your winters every April, or purchase an additional set of wheels, mount your winters to those, and mount/dismount them yourself whenever needs dictate.
- What should you do if you live somewhere warm, and only visit winter? You’re spending a ton of money on that hobby already. Delay the purchase of the latest set of skis until next year, and instead spend that money on a set of winter tires mounted to a spare set of wheels. Put them on before every trip, then take them off after. Driving in winter is too dangerous to go unprepared.