In short. In North America, an all-season tyre is usually marked only M+S, and M+S involves no snow performance test. An all-weather tyre carries the three-peak mountain snowflake (3PMSF), which means a tyre of that type beat a reference tyre by a set margin on packed snow: by 7% in braking under the UN rule used in Europe, or by 10 to 12% in traction under the Canadian and US rules. That symbol is what Quebec requires from 1 December to 15 March, so a North American all-season tyre is not legal there in winter, while an all-weather tyre is. British Columbia accepts both M+S and 3PMSF if the tread is at least 3.5 mm. The snow test says nothing about ice, where the tyre makers we read still put a dedicated winter tyre ahead. In Europe and the UK, an "all-season" tyre often carries 3PMSF, which makes it closer to a North American all-weather.
Three names, two symbols
The confusion starts with the words. We write "tyres" throughout; in Canada and the US the same products are "tires".
| Name on the shelf | Where the name is used | Usual sidewall marking | What the marking proves |
|---|---|---|---|
| All-season | Canada, US | M+S | No snow test: a tread design and specification |
| All-weather | Canada, US | 3PMSF, usually with M+S | Passed a standard snow traction test |
| All-season (or "4 seasons") | UK, Europe | Often 3PMSF and M+S; check the tyre | If 3PMSF is there, passed the UN snow test |
| Winter | Everywhere | 3PMSF, sometimes the Ice Grip symbol | Snow test passed; Ice Grip adds an ice test |
| Summer | Everywhere | Neither | Not designed for snow |
Michelin Canada says the M+S marking on an all-season tyre is not a winter rating, while all-weather tyres have "qualified for severe snow traction" (Michelin Canada, updated 28 July 2026). Michelin's UK site describes all-season tyres marked 3PMSF for a climate like Britain's, working from about −10 °C to +30 °C (Michelin UK, updated 24 November 2025). So a British driver's "all-season" and a Canadian driver's "all-weather" are often the same kind of tyre, and a Canadian "all-season" is not. Read the sidewall, not the name; our guide to reading a tyre's markings shows where the symbols sit.
What M+S means, and what it does not
The UN regulation on tyre approval defines a "snow tyre" as one whose tread pattern, compound or structure is designed to do better than a normal tyre in snow when moving off or keeping the vehicle moving (UNECE Regulation No. 117, definition 2.11). That definition contains no number. British Columbia's regulation describes the M+S route the same way: a tyre that meets "the specifications adopted by the Rubber Manufacturers Association to be labelled on a sidewall with the letters 'M' and 'S'" (Motor Vehicle Act Regulations, section 7.162). Michelin UK says tyres marked only M+S "offer only a slight improvement on very lightly snow-covered roads" and have not been assessed by an outside body. California's chain rules, which accept M+S tyres in some cases, describe a snow-tread tyre as having "a relatively deep and aggressive tread pattern compared with conventional passenger tread pattern" (Vehicle Code section 558, quoted by Caltrans). M+S is a statement about the tread design, not a test result.
What the 3PMSF test actually measures
There are two families of test behind the same symbol, and we read both texts.
| UN Regulation No. 117 (Europe, UK and other countries) | Canada, SOR/2013-198, s. 5(4) | United States, FMVSS 139, S3 | |
|---|---|---|---|
| Name in the text | Tyre for use in severe snow conditions | Winter tire | Snow tire |
| Test | ABS braking on packed snow, or traction under ASTM F1805 | Traction under ASTM F1805 | Traction under ASTM F1805-20 |
| Surface | Firmly compacted base of at least 3 cm with about 2 cm of medium-packed snow on top | Medium pack snow | Medium pack snow |
| Pass mark (passenger car tyres) | Snow index of at least 1.07 by braking, or 1.10 by traction, against the standard reference tyre | Traction index of at least 110 against ASTM E1136 (P195/75R14), or 112 against ASTM F2493 (P225/60R16 97S) | Traction index of at least 112 against ASTM F2493 |
| Conditions | Air between −2 and −15 °C; snow between −4 and −15 °C; braking measured between 25 and 10 km/h | Test load 74% of the rated load at test pressure | As in ASTM F1805-20 |
| Marking | Alpine symbol | Alpine Symbol on at least one sidewall | Alpine Symbol, at the maker's option |
Sources: UNECE Regulation No. 117, paragraph 6.4.1.1 and Annex 7 (revision 4, text read in French); Motor Vehicle Tire Safety Regulations, last amended 1 January 2025; 49 CFR 571.139. The full title of ASTM F1805, as the Canadian text gives it, is "Standard Test Method for Single Wheel Driving Traction in a Straight Line on Snow- and Ice-Covered Surfaces". We did not read the ASTM standard itself, which is sold, not published; the Canadian regulation specifies the medium pack snow surface.
What 1.07 means in metres. This is our own arithmetic. At constant deceleration, the distance needed to slow from one speed to another is (v1² − v2²) / 2a. If a tyre's mean deceleration is 1.07 times that of the reference tyre, its distance over the same speed band is 1 / 1.07 = 93.5% of the reference tyre's, about 6.5% shorter. That is a minimum, on packed snow, between 25 and 10 km/h, for the tyre type put through the test; it says nothing about ice, wet or dry roads, or how far above the minimum a given tyre is.
What the symbol leaves out. CAA-Québec, the Quebec motoring club, warned in 2019 that the snowflake only shows that a tyre passed a traction test in moderately deep snow, and asked whether the same tyre grips on bare ice or in freezing rain, which the symbol does not tell you (CAA-Québec, 31 October 2019, in French). The EU tyre label has a separate ice grip pictogram, assessed against ISO 19447, and the regulation makes sellers state that ice grip tyres are designed for roads covered with ice and compact snow and should be used only in very severe climate conditions (Regulation (EU) 2020/740). Michelin Canada describes an Ice Grip symbol used on some Canadian and Nordic tyres (Michelin Canada, what is a winter tire). None of the all-weather tyres in our sources was presented with the ice symbol.
The 7 °C line
Transport Canada says that "at temperatures below 7°C, all-season and summer tires begin to lose elasticity, leading to less traction", while winter tyres keep their grip at much lower temperatures (Transport Canada, modified 6 October 2025). Ontario's government repeats the 7 °C figure for all-season tyres (Ontario). Nokian says its all-weather tyres stay flexible below 7 °C, "a point where traditional all season tires begin to lose grip" (Nokian Tyres, 16 January 2026). Seven degrees is a rule of thumb, not a value in any regulation above. Our UK winter tyre guide looks at where the figure comes from and how often British temperatures fall below it.
What is legal where: the rules by jurisdiction
| Jurisdiction | Winter tyre rule | M+S all-season accepted? | 3PMSF all-weather accepted? | Text |
|---|---|---|---|---|
| Quebec | 1 December to 15 March, every tyre on a motorised road vehicle registered in Quebec (heavy vehicles, tool vehicles and farm machines excepted), and on any such vehicle rented out in Quebec | No | Yes | Regulation, art. 1 (in force 1 December 2019); pictogram only since 15 December 2014 |
| British Columbia | Winter tyres or chains on signed routes, 1 October to 30 April on most routes, 31 March on some | Yes, with 3.5 mm of tread | Yes, with 3.5 mm of tread | Motor Vehicle Act Regulations, s. 7.162 |
| Ontario | No obligation | — | — | Ontario.ca |
| Colorado | Traction Law on the I-70 between Dotsero and Morrison, 1 September to 31 May, and elsewhere when activated | Yes, with 3/16 in (4.76 mm) of tread | Yes, with 3/16 in of tread | CDOT |
| California | Chain controls R1 to R3 | Under R2, a 4WD or AWD vehicle with snow-tread (M+S) tyres on all four wheels, carrying chains | Through the M+S marking, which many 3PMSF tyres also carry; Caltrans does not mention the mountain symbol | Caltrans; Vehicle Code s. 558 |
| United Kingdom | No requirement | — | — | Michelin UK |
| New South Wales (Kosciuszko National Park) | 2WD vehicles carry chains from the June to the October long weekend; not compulsory for 4WD and AWD | The page does not mention tyre types | — | NSW National Parks |
Quebec. The regulation published on 1 October 2008 said that from 15 December 2014 a tyre designed for winter driving is one bearing the pictogram in its Schedule A, which it describes as a mountain with three peaks, the middle one highest, at least 15 mm wide and 15 mm high, with a six-pointed snowflake (Gazette officielle, 2008). The 2019 amendment set the current wording: from 1 December to 15 March, every tyre of a motorised road vehicle registered in Quebec must be designed for winter driving, and the rule also applies to anyone who rents out such a vehicle in Quebec, wherever it is registered (Gazette officielle, 2019). The Quebec government page adds that studded tyres also qualify, that they are allowed from 15 October to 1 May on passenger vehicles, taxis and commercial vehicles of 3,000 kg or less, that the fine is $200 to $300, and that vehicles registered outside Quebec are not covered (Québec.ca, updated 5 October 2026). An M+S-only all-season tyre does not meet that definition; an all-weather tyre with the pictogram does.
British Columbia. Section 7.162 of the Motor Vehicle Act Regulations says a winter tyre "must have at least 3.5 mm of tread depth" and must be labelled on a sidewall with either "the 3-peaked mountain and snowflake symbol" or "the letters 'M' and 'S'" (BC Laws). The ministry says the requirement runs from 1 October to 30 April on most routes and ends on 31 March on some highways outside mountain passes and high-snowfall areas (routes and dates). It calls M+S the minimum, says 3PMSF tyres, "which include all-weather tires", give better traction on snow and ice, and allows studded tyres from 1 October to 30 April (passenger vehicles). For visitors and rentals it says M+S tyres meet the minimum requirement (visitors). So the same all-season tyre that is not allowed on a Quebec-registered car in January is legal on a signed BC highway, as long as it keeps 3.5 mm of tread.
Colorado and California. Colorado's Traction Law asks for tyres with "a tread depth of at least 3/16-inch" that are winter tyres (mountain-snowflake), "all-weather rated" or M+S, or else chains or an alternative traction device; since autumn 2025 it applies to all 4WD and AWD vehicles too (CDOT; CDOT release, 20 November 2025). California's R2 control exempts 4WD and AWD vehicles with snow-tread tyres on all four wheels from fitting chains, provided they carry them; under R3 everyone fits chains (Caltrans). For chains on cars with large wheels, see snow chains and snow socks.
United Kingdom and Australia. Michelin UK states that "in the UK, there's no requirement to fit winter tyres at a particular time of the year" (Michelin UK, updated 8 September 2026); continental Europe has its own rules, in the same snow chains guide. In New South Wales, the national parks service asks 2WD vehicles to carry chains on set roads in Kosciuszko National Park in winter and says nothing about tyre types (NSW National Parks). We found no Australian winter tyre obligation in the pages we read.
All-weather or winter: what the tyre makers say
These are the makers' positions, not ours. Onyx Forged does not recommend a size or an offset, and does not choose a tyre for you.
| Driving conditions | What the sources say |
|---|---|
| Mild winters, rare snow, temperatures mostly above freezing (much of the UK) | Michelin UK presents 3PMSF all-season tyres for temperate climates and sudden cold spells; Nokian presents all-weather tyres for places where snow or ice arrives occasionally |
| Regular snow, cleared roads, cities (Toronto, Boston, Colorado) | Nokian names these cities among the places all-weather tyres suit; Michelin Canada calls all-weather tyres "the only truly year-round-safe option" for Canadian drivers |
| Persistent cold, ice, black ice, rural or mountain roads (much of Quebec, mountain roads) | Nokian: "dedicated winter (snow) tires are still superior in severe, icy conditions and persistent extreme winter weather"; Michelin UK: winter tyres remain the choice for heavy snow or ice; CAA-Québec points rural drivers to winter tyres and mountain roads to studs |
| Quebec, 1 December to 15 March | 3PMSF or studs required by law: winter or all-weather, not M+S all-season |
| BC signed routes | M+S or 3PMSF with 3.5 mm of tread; 3PMSF recommended by the ministry |
An all-weather set can stay on the car all year, with no second set of wheels and no twice-yearly change, but on ice the makers quoted above still put a winter tyre ahead. A winter set usually goes on a second set of wheels: our guides to alloy against steel wheels for winter and to storing tyres and wheels between seasons cover it. If you consider a different tyre size for winter, the size must be one listed for your car by its maker; our tyre size calculator shows how the diameter changes, and the car's documents decide what is allowed.
How long the snow rating lasts
The 3PMSF test is passed once by a tyre type, on a new tyre, and is not repeated as the tread wears. British Columbia's 3.5 mm minimum and Colorado's 3/16 inch (4.76 mm) are both well above the 1.6 mm general minimum the SAAQ quotes, which we read as a sign that regulators expect snow grip to fall away well before the tyre is legally worn out. CAA-Québec advises starting the winter with at least 6/32 inch of tread, also 4.76 mm. Nokian moulds a snowflake into the tread of one of its all-weather tyres that wears away when the tyre is no longer suited to snow or ice. The legal minimums by country are in our guide to legal tread depth, and age limits in how long tyres last. An all-weather tyre used all year wears through the summer too, so it reaches those depths sooner than a winter tyre used four months a year. If a tyre shows damage, a bulge or a cut, have it checked before driving on.
Two practical rules from the sources apply to every type. Transport Canada and Ontario say not to mix tyres of different types on one vehicle, and Ontario asks for four winter tyres, not two. Pressures are those on the car maker's placard.
Frequently asked questions
What does 3PMSF mean?
Three-peak mountain snowflake. It is the symbol on the sidewall of a tyre type that passed a standard snow test: under UN Regulation No. 117, braking on packed snow at least 7% better than a reference tyre, or traction 10% better; under the Canadian and US rules, a traction index of at least 110 or 112 against a reference tyre under ASTM F1805.
Is an all-weather tyre a winter tyre?
Legally, in Quebec, yes: Quebec requires the 3PMSF pictogram (or studs), and an all-weather tyre carries it. In terms of grip, the makers we read still place dedicated winter tyres ahead on ice and in persistent severe cold, because the 3PMSF test is run on packed snow only.
Are all-season tyres legal in winter in Canada?
In Quebec, M+S all-season tyres are not allowed from 1 December to 15 March on vehicles registered there. In British Columbia, M+S tyres with at least 3.5 mm of tread meet the winter tyre requirement on signed routes. Ontario has no winter tyre obligation.
Is M+S the same as 3PMSF?
No. M+S describes a tread design and involves no snow performance test; 3PMSF requires a test against a reference tyre. Many 3PMSF tyres also carry M+S: look for the mountain itself.
Do all-weather tyres work on ice?
The 3PMSF test does not include ice. The EU label has a separate ice grip pictogram under ISO 19447, intended for very severe conditions, and Michelin Canada describes an Ice Grip symbol on some winter tyres. We did not find an all-weather tyre presented with that symbol in the sources we read.
Can I keep all-weather tyres on all year?
That is what they are designed for, and in Quebec they remain legal in winter. They wear in summer too, so check the tread before each winter: BC requires 3.5 mm on signed routes and Colorado 3/16 inch during the Traction Law.
Do I need four winter or all-weather tyres?
The sources all say four. Quebec's rule covers every tyre on the vehicle, Ontario asks for four winter tyres, and Transport Canada advises against mixing tread types, constructions or sizes on one vehicle.
Onyx Forged is a French brand of made-to-order forged wheels, designed to JWL/VIA standards, for a summer or a winter set: see how to customise a set.
Sources
- Regulations and standards: UNECE Regulation No. 117 (revision 4, 2016, French text), definitions 2.11 and 2.11.1, paragraph 6.4 and Annex 7; Motor Vehicle Tire Safety Regulations, SOR/2013-198, s. 5(4); 49 CFR 571.139, S3 and S5.5(i); Regulation (EU) 2020/740, tyre labelling.
- Quebec: Gazette officielle, 1 October 2008 and 13 November 2019, in French; Québec.ca, winter tyres, in French; SAAQ, winter tires; CAA-Québec, in French.
- British Columbia: Motor Vehicle Act Regulations, s. 7.162; winter tire and chain-up routes; passenger vehicles; visitors and rentals.
- Canada and Ontario: Transport Canada, using winter tires; Ontario, winter driving.
- United States: Colorado DOT, Traction Law and release of 20 November 2025; Caltrans, chain controls.
- United Kingdom and Australia: Michelin UK, European winter tyre regulations; NSW National Parks, snow driving.
- Tyre makers: Michelin Canada, summer, winter and all-season tires; Michelin Canada, what is a winter tire; Michelin UK, what are all-season tyres; Nokian Tyres, all-weather vs winter tires.
All pages were read on 16 October 2026.
The Onyx Forged design office.