Snow tires, also known aswinter tires, aretires designed for use onsnow andice. Snow tires have atread design with larger gaps than those on conventional tires, increasingtraction on snow and ice and are often optimized to drive at temperatures below 7 °C (45 °F). Tires that meet specificstandards and or tests are entitled to displayM+S, aThree Peak Mountain Snow Flake (3PMSF), and or anIce Grip Symbol (IGS) on their sidewalls.Studded tires are a type of snow tires which have metal or ceramic studs that protrude from the tire to increase traction on hard-packed snow or ice and haveparallel standards including the use of the3PMSF symbol with aШ (the Cyrillic letter "Sha") along with "STUDDED" and theIGS. Studs abrade dry pavement, causing dust and creating wear in the wheel path.[2]Regulations that require the use of snow tires or permit the use of studs vary by jurisdiction.
All-season tires have tread gaps that are smaller than snow tires and larger than conventional tires. They are quieter than winter tires on clear roads, but less capable on snow or ice.[3]
Snow tires operate on a variety of surfaces, including pavement (wet or dry), mud, ice, or snow. The tread design of snow tires is adapted primarily to allow penetration of the snow into the tread, where it compacts and provides resistance against slippage.[4] The snow strength developed by compaction depends on the properties of the snow, which depend on its temperature and water content—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. New and powder snow have densities of 0.1 to 0.3 g/cm3 (6 to 20 lb/cu ft). Compacted snow may have densities of 0.45 to 0.75 g/cm3 (28 to 47 lb/cu ft).[5]
Snow or ice-covered roadways present lower braking and cornering friction, compared to dry conditions. The roadway friction properties of snow, in particular, are a function of temperature. At temperatures below −7 °C (20 °F), snow crystals are harder and generate more friction as a tire passes over them than at warmer conditions with snow or ice on the road surface. However, as temperatures rise above −2 °C (28 °F), the presence of free water increasingly lubricates the snow or ice and diminishes tire friction. Hydrophilic rubber compounds help create friction in the presence of water or ice.[6]
The compacted snow develops strength against slippage along a shear plane parallel to the contact area of the tire on the ground. At the same time, the bottom of the tire treads compress the snow on which they are bearing, also creating friction. 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/contact process works both in the direction of travel for propulsion and braking, but also laterally for cornering.[5]
The deeper the snow that the tire rolls through, the higher the resistance encountered by the tire, as it compacts the snow it encounters and plows some of it to either side. At some point on a given angle of uphill pitch, this resistance becomes greater than the resistance to slippage achieved by the tread's contact with the snow and the tires with power begin to slip and spin. Deeper snow means that climbing a hill without spinning the powered wheels becomes more difficult. However, the plowing/compaction effect aids in braking to the extent that it creates rolling resistance.[5]
Attributes that can distinguish snow tires from "all-season" and summer tires include the following:[6]
Wet-film conditions on hard-compacted snow or ice require studs or chains.[6]
Many jurisdictions in Asia, Europe, and North America seasonally allow snow tires with metal or ceramic studs to improve grip on packed snow or ice.(SeeRegulations)
Such tires are prohibited in other jurisdictions or during warmer months because of the damage they may cause to road surfaces.[7] The metal studs are fabricated by encapsulating a hard pin in a softer material base, sometimes called thejacket. The pin is often made oftungsten carbide, a veryhard high performance ceramic. The softer base is the part that anchors the stud in the rubber of the tire. As the tire wears with use, the softer base wears so that its surface is at about the same level as the rubber, whereas the hard pin wears so that it continues to protrude from the tire. The pin should protrude at least 1 millimetre (0.04 in) for the tire to function properly.[8] Studded tires do not eliminate skidding on ice and snow, but they greatly reduce risks.[9]
Studdable tires are manufactured with molded holes on the rubber tiretread. Usually, there are 80 to 100 molded holes per tire for stud insertion. The insertion is done by using a special tool that spreads the rubber hole so that a stud jacket can be inserted and theflange at the bottom of the jacket can be fitted nicely to the bottom of the hole. The metal studs come in specific heights to match the depths of the holes molded into the tire tread based on the tread depths. For this reason, metal studs can be inserted only when the tires have not been driven on. A proper stud insertion results in the metal jacket that is flush with the surface of the tire tread having only the pin part that protrudes.[10]
Regardless of what conditions a tire is designed to handle, regional authorities may require minimum tread depth such as 6/32 or 3/16-inch (~4.75mm) in the U.S.[11][12][13] or 4mm (~5/32in) in Europe[14][15][16], the use of chains[17][18][19][20], or close road access all together in freezing conditions.
The M+Stire code arose in the 1970s to indicate tires whosetread design performs better in "Mud and Snow" conditions than regular "non-M+S" street tires[21][22][23], and is distinct from the tire code "M+T" for "Mud and Terrain".
TheUSTMA includes requirements that M+S tire tread has recesses that extend at least 1/2 inch from the edge toward the center, with a minimal cross-section of 1/16 inch, and be angled to the direction of travel from 35 to 90 degrees (perpendicular)[24]. The Tire and Rubber Association ofCanada (TRAC, formerly the Rubber Association of Canada) also uses USTMA standards[25].
TheISO defines both "snow tyre"[26] and "mud and snow tyre"[26] as performing better at initiating or maintaining vehicle motion under their respective road condition versus a normal tire lacking the M+S designation or a similar combination of “M” and “S” (e.g. M&S).
UNRegulation No. 117[27] (UN R117) definitions and revisions have used M+S to indicate tires whose tread pattern, tread compound or structure are designed to outperform a normal tire in "mud and fresh or melting snow"[28]. Whether a tire has a "M+S marking (Y/N)" is included "grip index" test report forms[29].Reg. No. 172[27] requires a retreaded tire's sidewall to display M+S if so qualified[30]. Currently, 68 countries have signed toUN Regulations regarding tires, theUnited States and Canada being the two notable exceptions which use USTMA and their respective laws.
.jpg)
The Alpine Symbol or Three-Peak Mountain Snow Flake (3PMSF) pictogram depicts a "mountain profile" with "three peaks with the middle peak being the tallest" containing "a six-sided snowflake" half the height of the tallest peak is an international indicator of tires of various classes rated for "severe snow use", such as a passenger vehicle tire thatperforms 10 to 12% better in straight-line "traction test" than a Standard Reference Test Tire (SRTT) to meet USTMA's standard[31]. It is usedin addition and adjacent to the M+S mark, and was standardized in 1999[32].
Snow tires should be installed on all wheels, never just the front which could lead to adverse handling[33].
ISO defines a "severe snow use tyre"[26] as having a tread pattern, compound or structure whose snow grip is based on performance testing using ISO 18106 "Methods for measuring snow grip performance" to testbraking on snow for passenger car and commercial vehicle tires, andacceleration on snow for truck and bus tires[34].
The USTMA requires[31] the Snow Grip Index (SG)[35] of tires for "severe snow conditions" equal or exceed that of a SRTT using straight line "traction test"ASTM F1805-18[36] on a medium packed snow surface. For example, with the SRTT having a SG of 1.00, a 14-inch tire would need a SG of 1.10, and a 16-inch tire a SG of 1.12[37][38], basically 10 or 12% better respectively.
UN R117 requires "severe snow" tires for a passenger car (C1) to equal or exceed a "brake test" SG of 1.07 and "traction test" SG of 1.10, while light commercial (C2) have a lesser "brake test" SG of 1.02, whereas heavy duty (C3) vehicles only "acceleration test" SG of 1.25. Whether a tire has a "3PMSF marking (Y/N)" is also included grip index test report forms[29].Reg. No. 172[27] requires a retreaded tire's sidewall to display both the 3PMSF and M+S if so qualified[30].
The Ice Grip Symbol (IGS) depicting a "mountain profile" containing "three icicles with the middle icicle being the longest" is used internationally to indicate passenger car tires rated for "ice conditions" whichperform at least 18% better in straight-line "braking test" than a reference tire[39]. It is placedin addition and adjacent to both the 3PMSF mark (whose requirements it must also meet) and M+S mark, and was standardized in 2021.
Tires for "ice conditions" should be installed on all wheels, never just the front which could lead to adverse handling[33].
The USTMA requires[39] the Ice Grip Index (GI) of an "ice conditions" tire to equal or exceed 1.18 compared to a 16-inch tire meeting ASTM F2493[38] in a "braking test" complying with ISO 19447:2021[40].
UN R117 defines an "ice grip tyre" as 3PMSF-rated passenger car tire with aGI of 1.18 or greater using the same procedures used by USTMA[29].
ISO's definitions of tire industry terms (2017)[26] has yet to be updated since the release of their "ice grip performance" test methods in 2021[40].
A new symbol coupling the Alpine "3PMSF" symbol with theCyrillic letter "Sha" (Ш), the first letter ofstuds orspikes (Russian: Шипы"shipy"; Ukrainian: Шипи"shipi"), was standardized in 2022 forstudded tires that meet the requirements for "severe snow use", in addition to adding the word "STUDDED" at least 4mm in height to the tire sidewall[41][42]. Studded tires should be installed on all wheels, never just the front which could lead to adverse handling[33].
UN Regulation No. 164[42] (UN R164) was adopted in late 2022 to apply the "severe snow use" standards to studded tires, which are permitted in some regions yet were beyond the scope ofUN R117. The following year, UN R164 was amended to allowstudded tires that meet the requirements for a "ice grip tyre"[40] to add the Ice Grip Symbol (IGS)[43].
Whether to avoidrear-end collisions or damage from flung material, some countries have usedthe same Ш "Sha" in a red triangle on the rear of studded vehicles to alert following motorists (Russian law 1993-2018[44], Ukraine present[45]), a similar logo (Lithuania[46]), or aspiked tire logo (Austria).
Allprefectures of Japan, except for the southernmost prefecture ofOkinawa, have a traffic regulation requiring motorized vehicles to be fitted with winter tires ortire chains when the road is covered by ice or snow.[48][49] In addition, tire chains must be fitted for all vehicles on rural designated highways insnow country regions when regulated by traffic signs requiring tire chains.[50]
In many prefectures, tread grooves of snow tires are worn off for more than 50% of their original depth, tires must be replaced to meet the legal requirements.[48] Drivers will be fined for failing to comply with the snow tire or tire chains requirements, and checkpoints are in place on major highways.
Nationwide studded tire restrictions in Japan for passenger vehicles came into effect in April 1991, followed by restrictions for commercial trucks in 1993.[51] Studded tires are still legal in Japan, but their usage is restricted by environmental law and it is a criminal offence to operate a vehicle fitted with a studded tire on dry asphalt or concrete.[51]
.svg)
As of 2024, regulations pertaining to snow tires in Europe varied by country. The principal aspects of regulations were whether the use was mandatory and whether studded tires were permitted.[52][53]
NHTSA (United States) andTransport Canada allow the3PMSF symbol on tires that meet or exceed the industry requirement from a reference (non-snow) tire.[55][56] As of 2016, snow tires were 3.6% of the US market and 35% of the Canadian market.[57]
| Region | Snow tires | Snow chains | Studded tires |
|---|---|---|---|
| Alberta | |||
| British Columbia | MVAR 7.162 | MVAR 7.163 - 7.1634 | MVAR 7.164 |
| Manitoba | CCSM H60 3.21(2) | ||
| National parks of Canada | CRC c1126, 40 | CRC c1126, 40 | |
| New Brunswick | MVA M17 241(3) | MVA M17 241(3) | |
| Newfoundland and Labrador | CNLR 1007/96 27 | CNLR 1007/96 27 | CNLR 1007/96 28 |
| Northwest Territories | MVER 82.(b) | MVER 82.(a) | |
| Nova Scotia | MVA 293, 198(2) | RSNS 45/79 | |
| Nunavut | MVER 82.(b) | MVER 82.(a) | |
| Ontario | RSO 1990 H.8 69(2) | RRO 625, 9.(1) | |
| Prince Edward Island | "winter tires" | HTA 136.(3) | HTA WTR 1. |
| Quebec | C-24.2, r. 45 | C-24.2, r. 44 2. | C-24.2, r. 44 1. |
| Saskatchewan | |||
| Yukon | |||
| Region | Snow tires | Snow chains | Studded tires |
The U.S.National Highway Traffic Safety Administration Federally, Transport Canada advises drivers to use winter tires on snow- or ice-covered roads. Canada’s provinces, territories, and national parks also have various winter-tire and traction requirements, which differ by date, location, weather conditions, and vehicle classification.[58][59]
Quebec is the only jurisdiction that requires vehicles registered therein to have 3PMSF-rated or studded tires December 1 through March 15 regardless of weather.[60][61]
Some U.S. states, especially those in snowy or mountainous regions[11][12][13], require certain vehicles to use approved winter tires or carry traction devices such astire chains. when traveling on designated roads during the winter season. Where allowed, studded tires and similar traction devices are usually restricted to specific months to prevent road damage. Requirements can vary widely by jurisdiction and may also depend on vehicle class, axle configuration, weight, and other factors.[62][19]
Chain Requirement Levels ... There are Three Levels of Chain Requirements in California: Requirement 1 (R-1): ... Requirement 2 (R-2): ...Requirement 3 (R3): Chains or traction devices are required on all vehicles, no exceptions.
3.1.3 snow tyre; 3.1.5 severe snow use tyre; 3.3.15 mud and snow tyre
2.11. "Snow tyre" means a tyre whose tread pattern, tread compound or structure are primarily designed to achieve in snow conditions a performance better than that of a normal tyre with regard to its ability to initiate, maintain or stop vehicle motion ... 4.2.6. The inscription "M+S" or "M.S" or "M&S" in the case of a tyre designed to ensure in mud and fresh or melting snow a performance better than that of a normal tyre
2.13.1. 'Snow tyre for use in severe snow conditions' means a snow tyre ... that fulfills the requirements of paragraphs 6.5. and 6.5.1. of this Regulation.", "2.13.1.1. 'Ice grip tyre' means a class C1 snow tyre for use in severe snow conditions that is additionally designed to be used on road surfaces covered with ice", "4.2.6.1. The 'Ice Grip Symbol'", also "...marking (Y/N)" on pages 67, 68, 127, 128 under "Annex 5 – Appendix, Test reports examples of wet grip index for tyres in new state" and "Annex 9 – Appendix 2, Test reports examples of wet grip index for tyres in worn state
In 1999, The U.S. Tire Manufacturers Association (USTMA) and the Rubber Association of Canada (RAC) agreed on a performance-based standard to identify passenger and light truck tires that attain a traction index equal to, or greater than 110 (compared to a reference tire which is rated 100) during the specified American Society for Testing and Materials traction tests on packed snow.
4.3.2.
Studded tyres approved according to this Regulation shall also bear the word "STUDDED" at least 4 mm in height.
(machine translation) The requirement to install such a sign on vehicles equipped with studded tires has existed as long as the Russian Federation's Traffic Regulations themselves—since October 23, 1993. However, car owners were slow to comply, as the traffic regulations did not provide for an administrative penalty in the form of a fine for the absence of the sign. On April 4, 2017, the State Traffic Safety Inspectorate of the Russian Federation introduced a fine for the absence of a "Spikes" sign on vehicles with studded tires (provided that at least one stud remains on the tires). The fine is 500 rubles. ... Amendments came into force on July 1, 2018 , eliminating the requirement for drivers to install the "spikes" sign on vehicles with studded tires.
"30.3 ... л) "Шипи" ... 3.0.3 k) "Studs" - an equilateral white triangle with the top up and a red border, in which the letter "Ш" is inscribed in black (the side of the triangle is not less than 200 mm, the width of the border is 1/10 of the side). The sign is placed at the rear of vehicles equipped with studded tires.
5. The distinguishing sign depicting a white equilateral triangle with a red rim and a tire stud symbol in the middle must be affixed to the rear of the car with studded tires. The length of the side of the triangle is between 200 and 300 mm, the rim width is 1/10 of the side length.
{{cite news}}:|archive-url= requires|url= (help)Your vehicle must be winter-ready from December 1 to March 15...does not apply to trailers and vehicles registered outside of Québec... To be compliant, a tire designed for winter driving must be marked with the [3PMSF] or be studded... recommended depth is at least 4.8 mm.
