It is almost winter, and with the festivities coming, the typical debate about winter tires also comes in. For many car enthusiasts, the solution for the problem on how to drive in deep, unplowed snow is the winter tire. But there’s so much more to it than that. For most people, who are confused with tires and cars in general, a lot of questions pop into mind such as what makes a winter tire different from an all-season? What does science really say about winter tires? Are all-season tires aren’t really for all seasons?
We know you are curious to know if your all-season tires will really work? Well, to give an answer as early as now, yes they do for most drives, but as soon as the temperature goes down to almost the freezing point, the benefits of getting winter tires make the added cost and effort significantly worth it. So to help you understand, here are the things you should know (based on science) why you should buy a winter tire.
What are winter tires?
Image lifted from: https://www.mercedes-benz-brampton.ca/what-you-should-know-about-winter-tires/
Winter tires, also known as snow tires, are tires designed to be used on snow and ice. Unlike conventional tires, winter tires have a tread design with larger gaps which significantly increases the tire’s traction on snow and ice. Winter tires have to pass specific tests such as winter traction performance tests in order to verify that they are safe to be used on snow and ice. After passing such, the tires will be entitled to display a three-peak mountain snowflake symbol on their sidewalls. Winter conditions with temperatures below 7°C or 45 °F are the optimal states that the winter tires can drive in. Other manufacturers produce winter tires that come with some metal or ceramic studs that protrude from the tire. These metal and ceramic studs are able to increase traction on hard-packed snow or ice during winter. However, it must be noted that these metal or ceramic studs abrade dry pavement which causes dust to be released in the air. It also creates wear in the wheel path. With that, many countries across Asia, Europe, and North America have regulations that require the use of winter tires or permit the use of studs.
Road Conditions During Winter
There are a variety of surfaces on which winter tires operate. These include pavement, wet or dry, mud, ice, or snow. The tire design of winter tires are specifically made for it to adapt mainly on these surfaces. Furthemore, the tread design allows penetration of the snow into the tread, where it compacts and provides resistance against slippage. The compaction in the treads develops strength, which greatly depends on the properties of the snow. These properties are greatly affected by weather conditions such as temperature and water content. It must be noted that wetter, warmer snow compacts better than dry, colder snow up to a point where the snow is so wet that it lubricates the tire-road interface. A density of approximately 0.1 to 0.3 g/cm3 or 6 to 20 lb/cu ft are usually observed in new and powder snow. In compacted snow, however, a density of about 0.45 to 0.75 g/cm3 or 28 to 47 lb/cu ft is observed.
During winter, snow or ice-covered roadways pose significant risks to drivers because compared to dry conditions, snow causes lower braking and cornering friction. It must be noted that the roadway friction properties of snow to be specific are a function of temperature. Snow crystals are harder and produce more friction as a tire passes over them at temperatures below −7 °C or 20 °F compared to warmer conditions with snow or ice present on the surface of the road. As temperatures rise above −2 °C or 28 °F, tire friction is reduced because the presence of free water increasingly lubricates the snow or ice. Lastly, in the presence of water or ice, hydrophilic rubber compounds aid in producing friction.
Science behind Winter Tire
Slippage along a shear plane relative to the contact area of the tire on the surface on the ground are reduced due to the strength developed by the compacted snow. Furthemore, friction is also created at the same time as the bottom of the tire treads compress the snow on which they are bearing. The process of compacting snow within the treads requires it to be expelled in time for the tread to compact snow anew on the next rotation. The compaction or contact process functions both in the direction of travel for propulsion and braking and also laterally for cornering. It must be noted that there is a direct relationship between the resistance encountered by the tire and the depth of the snow. With that, the deeper the snow that the tire rolls through, the higher the resistance encountered by the tire. This occurs because as the tire compacts the snow it encounters and plows some of the snow to either side. In addition to that, the resistance created by the compact snow and the tire becomes greater than the resistance to slippage achieved by the tread’s contact with the snow at some point given at an uphill tread, and the tires with power begin to slip and spin. This means that without spinning the powered wheels, deeper snow indicates that climbing a hill becomes more difficult. However, rolling resistance is created due to the plowing or compaction effect which aids in braking.
Winter tire technology has been making huge progress over the past few years since its development. It must be noted that the first winter tires moved like paddles because they had ridges. Today, winter tire technology has advanced to develop its three primary areas:
- As stated above, snow can be compressed into the tire because there is empty volume between treads in the tire. The empty space permits the winter tire to move snow rather than ride on top of the snow like a paddle tire. In exchange, this provides better contact with the surface of the road. With that, winter technology all comes down to the tread pattern and the various grooves shaped into the rolling surface of the tire. There are various purposes with the various sizes present in the groove, however all of them function together in order to provide more grip in wet, snowy, or icy conditions. The function of the largest groove is to channel water out from under the part of the tire that contacts the road. This reduces hydroplaning, which usually occurs when a cushion of water builds up between the tire and the road.
- Sipes are also present in winter tires. These small yet fine slits that are designed in a unique configuration are observed in the winter tire’s tread pattern. As the tire comes in contact with snow, these sipes open in order to create more of a biting edge. In addition to that, these sipes can aid in removing water out from underneath the tire. Also, they function a slightly more counterintuitive purpose which is that they help to grab snow and hold it packed within the treads of the tire. Snow likes to stick to itself, that is why it is easy to make a snowball. With that concept in mind, a tire with a lot of sipes can behave like a snowball, with the snow that is packed into the treads gripping the snow on the road to give you increased traction.
- Winter tires have uniquely designed actual rubber compounds. It must be noted that rubber compounds found in all-season and summer tires become stiff and brittle as the temperature drops below 40 degrees Fahrenheit. With that, these tires’ flexibility is highly decreased during winter conditions, which results in lessening of their grip. Winter tires have rubber technology that can adapt to freezing temperatures, while also maintaining the flexibility of the rubber, which is vita in order to be able to grip the road. It is evident that the winter tire’s rubber compound retains its flexible properties in temperatures below even the freezing point.
Unfortunately, the tire’s dry-weather grip is slightly compromised due to all of these grooves and sipes compromise. Furthermore, it must be noted that summer tires for street cars follow this principle with minimal grooves. In addition to that, since they are expected to perform well in the wet weather of spring and fall, all-season tires have more grooves. In a winter tire, the dry handling functions are less of a priority than snow, ice and wet. In an all-season tire you are basically balancing dry, wet and snow, while for a summer tire you are balancing dry and wet.
Difference Between Winter Tires and All-Season Tires
Image lifted from: https://www.saltwire.com/wheels/winter-tires-dramatically-improve-safety-control-in-all-cold-weather-driving-conditions-255598/?location=nova-scotia
Here are some characteristics that differs winter tire from the usual all-season and summer tires:
- Improved friction on wet surfaces due to its hydrophilic rubber compounds
- Minimized resistance from the plowing effect of the tire through deeper snow due to a narrower aspect ratio between the diameter of the tire and the tread width
- An open, deep tread, with a high void ratio between rubber and spaces between the solid rubber
- Shoulder blocks, a specialized tread design at the outside of the tire tread to increase snow contact and friction
- More biting edges and improve traction on wet or icy surfaces due to added siping, or thin slits in the rubber.
- Wet-film conditions on hard-compacted snow or ice require studs or chains.
In many parts of the world such as in Asia, Europe, and North America, they seasonally permit the usage of winter tires that have metal or ceramic studs. These winter tires are allowed in order to improve grip on packed snow or ice of vehicles in these regions. However, during warmer or other seasons, these winter tires are usually not allowed because they can damage the surfaces of the road. When studs come into contact with road surface they damage the asphalt or concrete surface. This leads to creating polluting dust and wear in the wheel path that interferes with proper drainage. For this reason, studded tires are usually prohibited during warmer seasons, such as in many US states and some Canadian provinces. In addition to that, winter tires with studs are also noisy and uncomfortable, especially when they are utilized not on an icy or snowy road surface. Because studs are removed at higher speed, they should be utilized for highway driving.
In winter tires, jackets are observed which are basically metal studs that are fabricated by encapsulating a hard pin, which is frequently made of tungsten carbide, in a softer material base. It must be noted that the softer base is the part that anchors the stud in the rubber of the tire. Softer base wears as the tire wears with use. This results in the softer base’s surface to be about the same level as the rubber. The hard pin, on the other hand, wears so that it continues to protrude from the tire. In order for the tire to function properly, the pin should protrude approximately 1 millimetre or 0.04 inches.
It must be noted that winter tires do not eliminate skidding on ice and snow, however they significantly decrease the risks. In most cases, studdable tires are manufactured with molded holes on the tread pattern of rubber tires. Frequently, about 80 to 100 molded holes per tire are made for the insertion of the stud. Furthermore, based on the tread depths, the metal studs vary by specific heights in order to fit the depths of the holes molded into the tire tread. Because of this, stud metals can only be fixed when the tires have not yet been used. It must be remembered that a metal jacket that is flush with the surface of the tire tread having only the pin part that protrudes is the proof that the proper way of stud insertion was done.
- Braking Test
Braking is one of the most significant differences between an all-season tire and a winter tire. Studies have shown that braking from 12 mph down to a complete stop resulted in the vehicle equipped with winter tires to stop in just 34 feet, while the vehicle with all-season tires stopped at a distance of 57 feet. This indicates that the winter tire has provided more grip.
- Cornering Test
A 90-degree turn at a steady 11 mph comprised this cornering test. Results of this test showed that even after the stability control system kicked in and tried unsuccessfully to change the course, the car equipped with all-season tires had lost traction and wanted to plow straight ahead. While, the car with winter tires made the turn without losing traction.
Benefits of Winter Tires
Image lifted from: https://www.sullivantire.com/learn/tire-classroom/winter-tires-101
- Free of Compromise
As stated above, the unique design of rubber compounds of winter tires makes it significantly flexible. Furthermore, the winter tire’s one of a kind tread design makes it possible for exclusive use on snow, slush and ice and in cold temperatures. Drivers will surely benefit from highly increased traction during acceleration, especially in shorter stopping distances, and a drastic increase in directional stability at speed with no compromises made for other seasons. Unlike all-season tires that are somewhat good in the heat and somewhat good in the cold, winter tires are specifically made for cold-climate driving. With the compromise-free, the science and technology behind winter tires, drivers can definitely enjoy the cold weather drives and traveling on icy and snowy roads with a lot of peace of mind.
- Can Be Used On Roads That Are Not Just Icy and Snowy
When the temperature outside is so low, all-season or summer performance tires get significantly hard. This can be really dangerous because effective traction relies on tires being soft and malleable against the road surface. At about 7 C and below, the rubber in all-season and summer tires begin to harden, significantly reducing their ability to safely grip the road. Winter-specific tires are designed in order to continue to provide flexibility, even in sub-zero environments dipping as low as -30 C. In cold weather, even on dry roads, the softer, more flexible rubber utilized in the production of winter tires provides that all-vital give that all-season tires lose when it is cold outside. So to simply say, winter tires work better in the winter and even on dry roads.
- Maximized All Wheel Drive Performance
All Wheel Drive (AWD) is one of the most important selling points in today’s car market, especially in the Canadian shoppers. With the fast paced shifts in recent car models, swift-acting, precise and sophisticated all-wheel drive systems than ever before is vital. So whatever brand of car you are driving, whether it is a Subaru, Ford, Acura Hyundai or Mitsubishi, your car’s AWD system is important for supporting you to maintain vehicle control through reacting with millisecond precision to low-traction situations in order to keep you and your family safe. This is where also winter tires come into place. Winter tires maximize the AWD system’s performance. This is because the only way to increase the amount of physical traction between a vehicle and the road’s surface is through the tires. AWD systems are able to do more grip to work if paired with the proper tires for the season. With winter tires, it allows the AWD system to do its job with maximum effectiveness.
- Excellent traction
As stated above, the tread pattern of winter tires are uniquely designed in such a way that it features deeper and more significant siping, or thin slits formed horizontally across the tread. This design allows it to produce more movement and essentially hold onto ice as well as any snow that may be clinging to the road. In addition to that, a more aggressive tread pattern can also decrease the chance of snow accumulation.
- Increases The Tire Life Of Your All-Season Tires
Well, one of the benefits of owning your winter tires in the colder season is that it extends the life of your all-season tires. Swapping to a set of winter tires will surely take off some usage time from your all-season rubber, while it stays hidden in your garage during the winter season. With this, it can surely aid in offsetting the money you have spent for your winter tires.
- Better braking
Most studies have found out that in situations where there is increased danger, most drivers have the tendency to stomp on the brake pedal. With hard and season-inappropriate tires, this can pose a significant risk because tires are likely to respond by skidding over a cold, slippery surface. With the proper winter tires, you have a tire that stays soft and has a better chance of helping the vehicle regain composure in scenarios of panic. In fact, studies show that stopping distance for the winter tires can be up to 30% better compared to all-season tires.
- Enhances The Safety System Of Your Car
Today, cars come with many safety systems in order to keep drivers and their families safe. In recent years, there has been an increasing trend in installing highly advanced stability control systems, braking control systems and even hazard-detection features like pre-collision auto-braking in automobiles sold in the market. However,it must be noted that these safety systems such as anti lock brakes, electronic brakeforce distribution, traction assist and stability control systems do not produce traction. They can only aid in maximizing the utilization of traction that is currently available. With the winter tires, you are providing these systems with additional physical grip so that they can work better at keeping you and yours safe.
- Hydroplane Resistance
A layer of water a car can potentially slide uncontrollably over is created as the tires roll over frozen pavement. This occurs because the ice beneath melts. Winter tires significantly decrease this unpleasant phenomenon, termed as hydroplaning, through the utilization of unique and specialized grooves that move the water off to the side of the tire.
- It Can Be A Part Of The Law
In some parts of the world, riding winter tires is part of the law. In Quebec, winter tires are required during the winter season. If you are caught driving a car not equipped with winter tires, you will be charged and dealt with according to the law. Driving in certain regions requires vehicles to be equipped with winter tires, so it is important to check with yours before heading out in the snow, especially that each province regulates the use of winter tires differently.
- Easier Snow Manoeuvrability
During colder seasons, winter tires are usually offered in skinnier sizing compared to OEM. The narrower width increases the pounds per square inch of pressure exerted, resulting in the tires having an easier time cutting through snow rather than floating overtop of it.
What do you need to look for when buying your own set of winter tires?
One of the most important things you need to check first when buying your own winter tires is for the three mountain peaks icon. This particular icon is stamped into the sidewall of the tire, indicating that the tire meets the DOT definition of a true winter tire. If you are planning to buy winter tires from the big-name companies such as Michelin, Continental, Bridgestone, Pirelli and Goodyear, you can make sure they have this icon. Moreover, they also offer dedicated winter tires in different sizes. In other countries, there are also tire companies that specialize in the production of winter tires such as Nokian. Some automakers even recommend a specific model of tire for winter use, which could help you to select faster and easier. It is highly suggested that you do some research before buying your own winter tire. It is important to read reviews, check enthusiast forums, and talk to a knowledgeable tire dealer.
Does Having Both Winter And All-Season Tires Cost More Money?
Even when mounted on steel wheels, the upfront costs of an additional set of tires will set you back a few hundred dollars. However, there are definitely many other factors that make winter tires worth considering. One factor is the cost of an insurance deductible compared to when purchasing another set of winter tires. If you get into an accident that could have been avoided by upgrading to winter tires and your insurance deductible, then the additional cost of another set of tires has been nullified. Second, owning another set of tires also lengthens the life of your all-season tires, as you will be putting miles on the winter tires instead, as well as avoiding the added wear and tear of driving all-seasons under conditions that are not good for their utilization. But most important of all is the matter of your own personal safety as the result of a situation that could have been prevented.
It must be noted that one pair of winter tires and one pair of all-season tires utilized together on the same vehicle is a recipe for accident. Doing so may cost you half as much, however you can only get half the control of your vehicle. Consider that front-wheel-drive cars still depend on the rear wheels in order to maintain the vehicle balanced when weight shifts during a turn. Uncontrolled spinout or snap oversteer can occur when two winter tires on the front and two all-season tires on the back. On the other hand, massive understeer occurs if the car is rear-wheel drive while having a pair of all-seasons on just the front wheels.
In the end, it is vital that you test identical vehicles equipped with winter tires and all-season tires. However, it is highly suggested that if you want the best during the colder season, you go with the winter tires. Indeed, all-season tires can handle different driving conditions, but all-season tires lose their capabilities once temperatures decrease and reach the freezing point, moreso when accompanied by snow and ice. With that, winter tires are not just for those who live in regions with snow 365 days 24/7 a week. If you live in a place that gets snow seasonally, buying your own set of winter tires is definitely worth the cost.
- Demere, M. Edmunds. 2015. What You Need To Know About Winter Tires. Retrieved from: https://www.edmunds.com/car-reviews/features/inside-line-asks-who-needs-winter-tires.html. Retrieved on 13 November 2020.
- MotorTrend. 2018. Are Snow and Winter Tires Worth It?. Retrieved from: https://www.motortrend.com/news/are-snow-and-winter-tires-worth-it/. Retrieved on 13 November 2020.
- Ontario Motor Sales. 2018. Why Should You Buy Winter Tires?. Retrieved from: https://www.ontariomotorsales.com/gm-certified-service/why-buy-winter-tires/#:~:text=Winter%20tire%20treads%20are%20specifically,to%20keep%20you%20from%20sliding. Retrieved on 13 November 2020
- Perkins, C. Road And Track. 2018. Every Question You’ve Ever Had About Winter Tires, Answered. Retrieved from: https://www.roadandtrack.com/car-culture/buying-maintenance/a25238363/winter-tire-guide/. Retrieved on 13 November 2020.
- Yong, B. Open Road Auto Group. 2015. Five benefits of switching to winter tires. Retrieved from: https://openroadautogroup.com/blog/five-benefits-switching-winter-tires. Retrieved on 13 November 2020.