Dedicated winter tires: when they help, the snowflake symbol and why you fit all four
Pick, fit, check and store winter tires, and learn what they cannot do on ice
Safety Behind the Wheel Foundation built this guide from Transport Canada winter tire guidance, National Highway Traffic Safety Administration (NHTSA) tire advice, Federal Highway Administration (FHWA) road weather data, federal tire standards and published studies from Sweden and Finland. Every source is listed at the end.
What a dedicated winter tire does
Every stop, turn and start depends on four small patches of rubber touching the road. The grip those patches can hold is called traction. In winter, traction drops for two reasons. The road gets slick, and cold stiffens the rubber in tires not made for it.
Transport Canada notes that once it is colder than 7°C (about 45°F), the rubber in all season and summer tires starts to stiffen, and traction drops [1]. Soft, flexible rubber can grab the tiny bumps in the road surface. Winter tire rubber is made to stay soft and grippy well below that point [1].
The tread is different, too. Winter treads usually have deep, open grooves and many thin slits called sipes. The grooves pack with snow, and snow grips snow well. The sipes add edges that bite into slush and slick spots.
NHTSA, the federal vehicle safety agency, says winter tires outperform all season tires in deep snow [2]. It also warns that summer tires are not designed for below freezing weather, snow or ice [2].
“Dedicated” means the tire is built for winter first. You put it on in late fall and take it off in spring. Its main job is preventing collisions. More grip gives you more room to stop, steer and recover.
When winter tires help most, and who uses them
From 2019 to 2023, nearly 745,000 collisions a year were weather related, according to the Federal Highway Administration [3]. About 220,000 a year happened during snow, sleet, hail or freezing rain [3]. On average, those collisions killed 407 people and injured about 34,200 each year [3].
Winter tires are worth a close look if:
- You often drive when temperatures sit near or below 45°F.
- Your roads often have packed snow, slush or freezing rain.
- Your routes include hills, sharp curves or roads that are plowed late.
- You cannot easily stay home on storm days, as with many health care and shift workers.
- A new teen driver will use the car this winter.
Buyers include families, commuters and fleets that keep delivery and service vehicles running all winter. Your climate shapes the choice. This guide can help you start the talk with a tire shop.
Comparison compiled by Safety Behind the Wheel Foundation
Tire setups for different winters
| Your typical winter | Tire setup to consider |
|---|---|
| Long, cold winters with regular snow or ice | Dedicated winter tires on all four wheels |
| Cold snaps and some snow, but you can stay home on storm days | Healthy all season tires, or a year round tire with the snowflake symbol |
| Frost is rare and snow almost never falls | Healthy all season tires, with pressure checks as it cools |
Reading the sidewall: the snowflake symbol and other marks
The most useful mark on a winter tire is a small mountain with three peaks and a snowflake inside.
Federal rules define it. A “snow tire” must score at least 112 on a traction index in a test on medium packed snow, compared with a standard reference tire [4]. In plain terms, it must pull clearly better than a basic test tire on packed snow. A tire that meets that bar may carry the mountain and snowflake on its sidewall [4]. Transport Canada also tells shoppers to look for the symbol, since it shows the tire met snow traction requirements [1].
Read the symbol for what it is: a pass mark, not a ranking. Two tires with the symbol can perform quite differently. The test is also run on packed snow, not ice [4]. So the symbol says nothing direct about grip on black ice.
“M+S” or “M/S” means mud and snow, and you will see it on many all season tires. NHTSA says all season tires have some mud and snow ability [2]. But only the mountain and snowflake symbol is tied to the federal snow test [4].
Many tires also carry government grades for treadwear, traction and temperature. Those grades do not apply to deep tread, winter type snow tires [5]. Where a traction grade does appear, it comes from straight ahead braking tests on wet pavement and does not include cornering [5].
Comparison compiled by Safety Behind the Wheel Foundation
What sidewall marks tell you
| Mark | What it tells you | What it does not tell you |
|---|---|---|
| Mountain and snowflake | Passed a packed snow traction test [4] | How well the tire grips on ice |
| M+S or M/S | Some mud and snow ability [2] | Whether it passed the federal snow test [4] |
| Traction grade (AA, A, B or C) | Straight ahead braking on wet pavement [5] | Snow, ice or cornering grip |
| Last four digits of the DOT code | Week and year the tire was made [2] | How the tire was stored |
The DOT code is the tire identification number on the sidewall. A code ending in 0308, for example, means the tire was made in the third week of 2008 [2].
Why you fit all four
Transport Canada advises installing winter tires in sets of four [1]. Safety Behind the Wheel Foundation gives drivers the same advice. Handling improves when all four tires share the same size, type, load index and speed rating [1]. Mixing tread patterns, internal construction or sizes makes a vehicle less stable [1].
The reason is balance. A car steers and stops predictably when front and rear grip are close to equal. When they are not:
- Winter tires only on the front. The rear tires lose grip first in a turn or hard stop, and the back end swings out. This is oversteer, or fishtailing.
- Winter tires only on the rear. The front tires slide first, and the car keeps going straight as you turn the wheel. This is understeer, or plowing.
Oversteer is a common way winter wrecks begin. A Swedish study reviewed in depth investigations of fatal crashes on roads covered with ice or snow. Loss of control was a major factor in 64% of them [6]. In 82% of those loss of control crashes, the car oversteered before the collision [6]. Uneven grip front to rear makes that kind of slide more likely.
All wheel drive helps you get moving, but every tire shares the work of braking and steering. Our guide to driving in snow and ice covers how drive systems behave on slick roads.
Two more fitting details matter:
Choosing the right winter tires for your vehicle
Start with the facts printed on your car, not a sale flyer. The vehicle maker’s recommended tire pressure is in the owner’s manual and on a label on the driver’s door frame [7]. NHTSA advises buying tires the same size as the originals, or another size the vehicle maker recommends [2]. Their load capacity and speed rating should match the originals too [8].
Next, decide two things. First, studded or studless: rules on studs vary by state and season, so check with your state DOT or DMV. Second, whether to buy a spare set of wheels. Mounting winter tires on their own wheels makes each seasonal swap quicker. If you do, ask about tire pressure sensors. Transport Canada warns that the warning system may not work unless the right sensors for your vehicle are installed [9].
You can buy winter tires at tire shops, auto parts stores, repair shops and dealer service departments. Some online sellers ship to a local installer. Mounting and balancing need special equipment, so have a qualified shop do that work. Shop early, before the first storm rush.
Ask about tire registration. Federal rules require independent tire dealers to give each buyer a registration form at the time of sale [10]. The system exists so tire makers can notify buyers about defective tires [11].
Studded, studless and the hard limits of ice
Studs are small metal pins set into the tread to dig into ice. Studless winter tires rely on soft rubber and sipes instead. Research on both shows the same lesson: tires help on ice, but they cannot make it safe.
The Swedish study compared cars on studded tires with cars on approved studless winter tires. On roads covered with ice or snow, studded tires were linked to 42% fewer fatal crashes [6]. Yet loss of control was still a major factor in 59% of fatal crashes with studded tires [6]. On dry or wet winter roads, studs showed no safety benefit [6]. The same research found that electronic stability control (ESC) cut winter injury crashes by 29% [6]. ESC brakes single wheels to help keep a car from sliding sideways.
A Finnish study of 958 fatal accidents from 1997 to 2012 found no significant overall difference between studded and studless winter tires [12]. On bare ice, though, risk in the later years was much higher for studless tires [12].
A Swedish study tested bus tires on ice, then used a driving simulator with strong side wind. Studless winter tires gave little or no gain over summer tires, while studded tires cut the risk of running off the road [13]. Drivers also found it very hard to judge ahead of time how a tire setup would perform [13].
What that means for you:
- The snowflake symbol is earned on packed snow, not ice [4].
- Grip that feels good at low speed can vanish on a bridge deck or shaded curve.
- Slow down, brake gently and leave a longer gap. Our following distance guide explains how much time to add.
- When ice is forecast, the safest choice is often not to drive.
Installing, checking and wearing out winter tires
Plan to install winter tires when daily temperatures start to stay below about 45°F, where all season rubber begins to stiffen [1]. Aim to have them on before the first snow.
Cold air lowers tire pressure, by about 1 psi for every 5°C (9°F) drop [8]. NHTSA advises checking at least monthly, with tires that have not been driven for three hours [7]. Fill to the door label number, never the maximum printed on the tire [7].
Grip fades steadily as tread wears down [1]. On snow, the loss shows up well before the tire is worn out. NHTSA says tires should be replaced once tread is down to 2/32 of an inch [2]. Transport Canada advises against using tires worn close to 4 mm (5/32 of an inch) on snow covered roads [1]. Rotate as the owner’s manual says [8]. Replace any tire with cuts, cracks, blisters or bulges [8].
Your fall swap routine
- Check each stored tire’s DOT date, tread depth and sidewalls.
- Replace any damaged or worn tire so the set stays matched.
- Mount the deepest tread pair on the rear, with directional tires on the correct side.
- Set cold pressure to the door label number.
- Have the wheel nuts tightened to the vehicle maker’s specification.
- Make sure the tire pressure warning light goes off, and recheck pressure after the first deep cold snap.
Mistakes to avoid
- Buying two winter tires instead of four.
- Treating the snowflake symbol as an ice rating.
- Keeping winter tires for another season after they wear to about 5/32 of an inch.
- Mixing studded and studless tires, or two different tread patterns.
- Driving faster because the car feels planted on snow. Extra grip is a safety margin, not permission to speed.
Storing the off season set
How you store a tire affects how long it stays safe. NHTSA lists sunlight, warm climates and poor storage among the things that speed up tire aging [2]. Some vehicle and tire makers recommend replacing tires that are six to 10 years old, no matter how much tread is left [2].
Transport Canada advises storing tires upright in a clean indoor space [8]. Keep them away from sunlight, strong artificial light, heat, fuels and oils, and ozone, a gas given off by electric motors [8]. For a set kept mounted on wheels, it advises dropping the pressure to about 15 psi to avoid cracking and deformation [8].
Frequently asked questions
Are all weather tires the same as dedicated winter tires?
Not quite. Some tires sold for year round use also carry the mountain and snowflake symbol, so they passed the same packed snow test [4]. But the symbol is a pass mark, not a ranking, and it does not measure ice grip. If you face long, cold winters with frequent ice, a dedicated winter tire is built for those conditions first. Ask a tire professional to compare options for your car and roads.
How long do winter tires last?
It depends on miles, storage and age. Because you use them only part of the year, a set may last several winters. For snow, Transport Canada advises against tires worn close to 5/32 of an inch [1]. Age matters too. Some vehicle and tire makers recommend replacing tires that are six to 10 years old, regardless of tread [2]. Check the DOT date code each fall.
Do I still need winter tires if my car has stability control?
They work as a team. In Swedish research, stability control cut winter injury crashes by 29% [6]. But stability control works by braking individual wheels, so it can only use the grip the tires provide. Good winter tires give it more to work with. Neither one makes ice safe.
What if one winter tire is damaged in the middle of winter?
Try to replace it with the same model and size so the set stays matched. Transport Canada warns against mixing tread patterns, construction and sizes [1]. If the new tire has much deeper tread than the others, ask the shop whether to replace more than one. The best tires belong on the rear axle [1]. Until the set is matched again, drive slower and leave extra room.
Can winter tires lower my insurance costs?
Sometimes. Transport Canada notes that some insurers may offer a discount to drivers who use winter tires [1]. Ask your insurer or agent. The bigger payoff is avoiding a collision, which can mean injuries, lost work time and a family left without a car.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation encourages drivers who face regular snow and ice to fit winter tires on all four wheels and still drive slowly. Dedicated winter tires are one of the most direct ways to add grip when roads turn cold, slushy and white. Choose tires with the mountain and snowflake symbol, match them to your vehicle’s ratings and fit all four. Keep them inflated, retire them when the tread gets low and store the off season set somewhere cool, dark and dry.
Then drive as if the tires were ordinary. Winter tires widen your safety margin, but ice can erase it fast. Slow speeds, long gaps and the choice to wait out a storm are still your best protection.
Related articles
- Driving in snow and ice: grip, black ice, skids and when to stay home
- Vehicle maintenance for safety: tires, brakes, lights and warning signs
- Car emergencies while driving: blowouts, brake failure and skids
- Safe following distance: the 3 second rule and when to add more
- Journey management for work drivers: weather, breakdowns and check ins
Sources and further reading
- 1Transport Canada. Using winter tires. Date modified October 6, 2025. tc.canada.ca/…/using-winter-tires
- 2National Highway Traffic Safety Administration. Tire Safety Ratings and Awareness (TireWise). Accessed October 2026. nhtsa.gov/vehicle-safety/tires
- 3Federal Highway Administration, Road Weather Management Program. How Do Weather Events Affect Roads? Accessed October 2026. Data year: 2019 to 2023 (five-year averages based on NHTSA data). ops.fhwa.dot.gov/weather/q1_roadimpact.htm
- 4Electronic Code of Federal Regulations. 49 CFR 571.139, Standard No. 139; New pneumatic radial tires for light vehicles (definition of snow tire and Alpine symbol). Up to date as of October 1, 2026. ecfr.gov/…/section-571.139
- 5Electronic Code of Federal Regulations. 49 CFR 575.104, Uniform tire quality grading standards. Up to date as of September 30, 2026. ecfr.gov/…/section-575.104
- 6Strandroth J, Rizzi M, Olai M, Lie A, Tingvall C. The effects of studded tires on fatal crashes with passenger cars and the benefits of electronic stability control (ESC) in Swedish winter driving. Accident Analysis and Prevention, published online December 2011 (via PubMed; doi:10.1016/j.aap.2011.11.005). Data year: Swedish in-depth fatal crash investigations (years not stated in abstract); police-reported crashes, winters 2003-2010. pubmed.ncbi.nlm.nih.gov/22269484
- 7National Highway Traffic Safety Administration. Winter Weather Driving Tips: Prepare Your Vehicle. Accessed October 2026. nhtsa.gov/winter-driving-tips
- 8Transport Canada. Riding on air (tire maintenance). Date modified December 11, 2013. tc.canada.ca/…/riding-air
- 9Transport Canada. Tire pressure monitors. Accessed October 2026. tc.canada.ca/…/tire-pressure-monitors
- 10Electronic Code of Federal Regulations. 49 CFR 574.8, Information requirements, tire distributors and dealers. Up to date as of October 2, 2026. ecfr.gov/…/section-574.8
- 11Electronic Code of Federal Regulations. 49 CFR 574.2, Purpose (tire identification and recordkeeping). Up to date as of October 2, 2026. ecfr.gov/…/section-574.2
- 12Malmivuo M, Luoma J, Porthin M. Studded and unstudded winter tires in fatal road accidents in Finland. Traffic Injury Prevention, 2016 (via PubMed; doi:10.1080/15389588.2016.1243239). Data year: 1997 to 2012 (November to March crashes). pubmed.ncbi.nlm.nih.gov/27700192
- 13Hjort M, Jansson J. Handling of buses on slippery roads during the influence of side wind: a study of the effects of different tyres. Accident Analysis and Prevention, 2010 (via PubMed; doi:10.1016/j.aap.2009.04.011). pubmed.ncbi.nlm.nih.gov/20380927
This article reflects the safety priorities of winter driving and everyday tire care. It is general safety education, not legal, insurance or financial advice, and it does not endorse any tire brand or seller. Rules change, so verify details with official sources. For your own vehicle, check the owner's manual and talk with a qualified tire professional. For local rules on studs or chains, contact your state DOT or DMV. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Dedicated winter tires: when they help, the snowflake symbol and why you fit all four.” drivewithcare.org, https://drivewithcare.org/dedicated-winter-tires/. Reviewed October 2026.
Special thanks to our contributors
We appreciate the professionals, experts, and community members who share their knowledge and perspectives to help make this resource better. Your insights are always welcome and appreciated.
Have professional expertise, firsthand experience, or a perspective that could make this resource better?
We welcome your input. Your knowledge and experience can help us make this resource more useful, accurate, and meaningful to the people who rely on it.
Thank you. Your contribution is on its way.
We’re grateful you took the time to share your knowledge with us. Our team reviews every contribution with care. If it helps improve this resource, we’ll update the page and recognize you the way you chose.
Keep learning
Safe Driving Resource Center
Guides, self-checks and articles for drivers, parents of new drivers, and families recovering after a crash.
