Snow tire

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Winter tire, showing tread pattern designed to compact snow in the gaps. Studless tire 2.jpg
Winter tire, showing tread pattern designed to compact snow in the gaps.

Snow tires, also known as winter tires, are tires designed for use on snow and ice. Snow tires have a tread design with larger gaps than those on conventional tires, increasing traction on snow and ice. Such tires that have passed a specific winter traction performance test are entitled to display a 3PMSF (Three-Peak Mountain Snow Flake) symbol on their sidewalls. Tires designed for winter conditions are optimized to drive at temperatures below 7 °C (45 °F). 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. 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 country in Asia and Europe, and by state or province in North America.

Contents

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]

Roadway conditions in winter

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]

Dry and moist snow conditions on roadways

Treads

Snow tire with metal studs, which improve traction on icy surfaces. Spikereifen.JPG
Snow tire with metal studs, which improve traction on icy surfaces.
Nokian bicycle winter tyre Nokian Hakkapeliitta W240.jpg
Nokian bicycle winter tyre

Attributes that can distinguish snow tires from "all-season" and summer tires include: [6]

Wet-film conditions on hard-compacted snow or ice require studs or chains. [6]

Studs

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. 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 the jacket. The pin is often made of tungsten carbide, a very hard 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] Snow 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 tire tread. 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 the flange 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, stud metals can only be inserted 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]

Tire/snow interactions

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]

Tire/snow interactions

Regulations

Tire showing the ASTM 3PMSF (Three-Peak Mountain Snow Flake) symbol, denoting a qualifying snow tire, and a separate snow flake symbol, that recommends tire replacement with 4 millimetres (0.16 in) of tread remaining Winter tires with North American symbol.jpg
Tire showing the ASTM 3PMSF (Three-Peak Mountain Snow Flake) symbol, denoting a qualifying snow tire, and a separate snow flake symbol, that recommends tire replacement with 4 millimetres (0.16 in) of tread remaining

ASTM International (American Society for Testing and Materials International) is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. The pertinent standard for snow tires is ASTM F1805 – 16, Standard Test Method for Single Wheel Driving Traction in a Straight Line on Snow- and Ice-Covered Surfaces, which assess tire performance on snow and ice. It measures the traction of tires under acceleration in the rolling direction. [12] Tires that pass this test are entitled to display the 3PMSF (Three-Peak Mountain Snow Flake) symbol. [13]

Asia

All prefectures of Japan, except for the southernmost prefecture of Okinawa, have a traffic regulation requiring motorized vehicles to be fitted with winter tires or tire chains when the road is covered by ice or snow. [14] [15] In addition, tire chains must be fitted for all vehicles on rural designated highways in snow country regions when regulated by traffic signs requiring tire chains. [16]

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. [14] 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. [17] 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. [17]

Europe

A Czech road sign Winter equipment, which mandates the use of snow tires CZ-C15a Zimni vybava.png
A Czech road sign Winter equipment, which mandates the use of snow tires

As of 2016, 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. [18] [19]

Russian studded tires warning sticker. Venalainen nastarenkaasta varoittava merkki auton perassa..jpg
Russian studded tires warning sticker.

North America

The U.S. National Highway Traffic Safety Administration (NHTSA) and Transport Canada allow display of a 3PMSF symbol to indicate that the tire has exceeded the industry requirement from a reference (non-snow) tire. [21] [22] As of 2016, snow tires were 3.6% of the US market and 35% of the Canadian market. [23]

US states and Canadian provinces control the use of snow tires. [24] Of these, Quebec is the only jurisdiction that requires snow tires throughout. [25] Some may require snow tires or chains only in specified areas during the winter. [26] [27] [28]

See also

Related Research Articles

<span class="mw-page-title-main">Tire</span> Ring-shaped covering that fits around a wheels rim

A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, which also provide a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over by providing a bearing pressure that will not deform the surface excessively.

<span class="mw-page-title-main">Racing slick</span> Type of tire used in auto racing

A racing slick or slick tyre is a type of tyre that has a smooth tread used mostly in auto racing. The first production slick tyre was developed by M&H Tires in the early 1950s for use in drag racing. By eliminating any grooves cut into the tread, such tyres provide the largest possible contact patch to the road, and maximize dry traction for any given tyre dimension; see Performance. Slick tyres are used on race tracks and in road racing, where acceleration, steering and braking require maximum traction from each wheel. Slick tyres are typically used on only the driven (powered) wheels in drag racing, where the only concern is maximum traction to put power to the ground, and are not used in rallying.

<span class="mw-page-title-main">Aquaplaning</span> Loss of traction due to water buildup under tires

Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or other wheeled vehicle occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction that prevents the vehicle from responding to control inputs. If it occurs to all wheels simultaneously, the vehicle becomes, in effect, an uncontrolled sled. Aquaplaning is a different phenomenon from when water on the surface of the roadway merely acts as a lubricant. Traction is diminished on wet pavement even when aquaplaning is not occurring.

<span class="mw-page-title-main">Tire tread</span> Rubber on the circumference of a tire that contacts the ground

The tread of a tire or track refers to the rubber on its circumference that makes contact with the road or the ground. As tires are used, the tread is worn off, limiting its effectiveness in providing traction. A worn tire can often be retreaded.

<span class="mw-page-title-main">Rolling resistance</span> Force resisting the motion when a body rolls on a surface

Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation of the wheel, roadbed, etc., is recovered when the pressure is removed. Two forms of this are hysteresis losses, and permanent (plastic) deformation of the object or the surface. Note that the slippage between the wheel and the surface also results in energy dissipation. Although some researchers have included this term in rolling resistance, some suggest that this dissipation term should be treated separately from rolling resistance because it is due to the applied torque to the wheel and the resultant slip between the wheel and ground, which is called slip loss or slip resistance. In addition, only the so-called slip resistance involves friction, therefore the name "rolling friction" is to an extent a misnomer.

<span class="mw-page-title-main">Ice racing</span> Form of racing that uses various vehicles on ice

Ice racing is a form of racing that uses cars, motorcycles, snowmobiles, all-terrain vehicles, or other motorized vehicles. Ice racing takes place on frozen lakes or rivers, or on groomed frozen lots. As cold weather is a requirement for natural ice, it is usually found at higher latitudes in Canada, the northern United States, and in northern Europe, although limited indoor events are held in warmer climates, typically on ice hockey rinks. Tracks in North America vary from 1/4 mile to several mile-long circuits.

<span class="mw-page-title-main">Adhesion railway</span> Railway which relies on adhesion traction to move a train

An adhesion railway relies on adhesion traction to move the train, and is the most widespread and common type of railway in the world. Adhesion traction is the friction between the drive wheels and the steel rail. Since the vast majority of railways are adhesion railways, the term "adhesion railway" is used only when it is necessary to distinguish adhesion railways from railways moved by other means, such as by a stationary engine pulling on a cable attached to the cars or by railways that are moved by a pinion meshing with a rack.

<span class="mw-page-title-main">Snow chains</span> Devices fitted to the tires of vehicles to improve traction on snow and ice

Snow chains, or tire chains, are devices fitted to the tires of vehicles to provide increased traction when driving through snow and ice.

Cadence braking or stutter braking is a driving technique that involves pumping the brake pedal and is used to allow a car to both steer and brake on a slippery surface. It is used to effect an emergency stop where traction is limited to reduce the effect of skidding from road wheels locking up under braking. This can be a particular problem when different tires have different traction, such as on patchy ice for example. Its use in an emergency requires a presence of mind that the situation itself might preclude. Cadence braking is supposed to maximize the time for the driver to steer around the obstacle ahead, as it allows the driver to steer while slowing. It needs to be learned and practiced. For most drivers of modern cars, it has been entirely superseded by ABS, however it is still a valuable skill for drivers of non-ABS equipped vehicles such as classic cars.

Traction, traction force or tractive force is a force used to generate motion between a body and a tangential surface, through the use of either dry friction or shear force.

<span class="mw-page-title-main">Siping (rubber)</span> Process to improve rubbers traction

Siping is a process of cutting thin slits across a rubber surface to improve traction in wet or icy conditions.

<span class="mw-page-title-main">Uniform Tire Quality Grading</span> Standards for passenger car tires

Uniform Tire Quality Grading, commonly abbreviated as UTQG, is the term encompassing a set of standards for passenger car tires that measures a tire's treadwear, temperature resistance and traction. The UTQG was created by the National Highway Traffic Safety Administration in 1978, a branch of the United States Department of Transportation (DOT). All tires manufactured for sale in the United States since March 31, 1979 are federally mandated to have the UTQG ratings on their sidewall as part of the DOT approval process, in which non-DOT approved tires are not legal for street use in the United States. It is not to be confused with the tire code, a supplemental and global standard measuring tire dimensions, load-bearing ability and maximum speed, maintained by tire industry trade organizations and the International Organization for Standardization.

A wheelspin occurs when the force delivered to the tire tread exceeds that of available tread-to-surface friction and one or more tires lose traction. This leads the wheels to "spin" and causes the driver to lose control over the tires that no longer have grip on the road surface. Wheelspin can also be done intentionally such as in drifting or doing a burnout.

<span class="mw-page-title-main">Road slipperiness</span> Low skid resistance condition

Road slipperiness is a condition of low skid resistance due to insufficient road friction. It is a result of snow, ice, water, loose material and the texture of the road surface on the traction produced by the wheels of a vehicle.

<span class="mw-page-title-main">Bicycle tire</span> Tire that fits on the wheel of a bicycle

A bicycle tire is a tire that fits on the wheel of a bicycle or similar vehicle. These tires may also be used on tricycles, wheelchairs, and handcycles, frequently for racing. Bicycle tires provide an important source of suspension, generate the lateral forces necessary for balancing and turning, and generate the longitudinal forces necessary for propulsion and braking. Although the use of a pneumatic tire greatly reduces rolling resistance compared to the use of a rigid wheel or solid tire, the tires are still typically, the second largest source, after wind resistance, of power consumption on a level road. The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the safety bicycle.

<span class="mw-page-title-main">Off-road tire</span>

Off-road tires are a category of vehicle tires that use deep tread to provide more traction on unpaved surfaces such as loose dirt, mud, sand, or gravel. Compared to ice or snow tires, they lack studs but contain deeper and wider grooves meant to help the tread sink into mud or gravel surfaces.

Floor slip resistance testing is the science of measuring the coefficient of friction of flooring surfaces, either in a laboratory or on floors in situ. Slip resistance testing is usually desired by the building's owner or manager when there has been a report of a slip and fall accident, when there has been a report of a near accident, or (preferably) before the flooring is installed on the property. Flooring is tested using a tribometer to discover if there is a high propensity for slip and fall accidents on it, either dry and/or when wet with water or lubricated with other contaminants such as kitchen grease, hydraulic oil, etc. There have been numerous floor slip resistance testing tribometers and lab devices produced around the world to measure both the static (stationary) and dynamic coefficient of friction, but presently there are only a few that have been proven to be reliable for obtaining useful safety results and that have current official test methods. Static coefficient of friction (SCOF) testing has always been unreliable for assessing safety in the wet condition, so any reliable slip resistance test will be measuring the available slip resistance to someone who is moving (dynamic) across the floor, and therefore will be assessing dynamic coefficient of friction (DCOF). If an instrument has no official published test method, or has a withdrawn test method, then there is a problem with the instrument, often being poor precision.

<span class="mw-page-title-main">Outline of tires</span> Overview of and topical guide to tires

The following outline is provided as an overview of and topical guide to tires:

<span class="mw-page-title-main">Snow socks</span> Devices fitted to the tires of vehicles

Snow socks are textile alternatives to snow chains. Snow sock devices wrap around the tires of a vehicle to increase traction on snow and ice. Snow socks are normally composed of a woven fabric with an elastomer attached to the inner and/or outer edge. The woven fabric covers the tire tread and is the contact point between the vehicle and the road. The elastomer keeps the snow sock in place and facilitates with installation. Some snow sock models have an additional component that covers the rim of the tire, which prevents snow or debris from gathering between the tread of the tire and the inner side of the woven fabric.

<span class="mw-page-title-main">Bar grip</span>

Bar grip tyres, or 'NDT' in US military parlance, are an early tyre tread pattern developed for off-road use.

References

  1. ↑ Heißing, Bernd; Ersoy, Metin (2010). Chassis Handbook: Fundamentals, Driving Dynamics, Components, Mechatronics, Perspectives. Springer Science & Business Media. p. 591. ISBN   9783834897893.
  2. ↑ "Prall Tester - Studded Tyre Wear Test". www.cooper.co.uk. Cooper Research Technology Ltd. Retrieved 1 September 2014.
  3. ↑ Newton, Richard (2007). Wheel and Tire Performance Handbook. St. Paul: MotorBooks International. p. 35. ISBN   9781610592512.
  4. ↑ Taylor, Rich (January 1985), "How to pick the right winter tires", Popular Mechanics: 72–78
  5. 1 2 3 Hays, Donald (2013). The Physics of Tire Traction: Theory and Experiment. Springer Science & Business Media. p. 428. ISBN   9781475713701 . Retrieved 25 December 2016.
  6. 1 2 3 Glenne, Bard (December 1989), "All about Snow Tires", Skiing: 52–55, 272
  7. ↑ ScienceDaily (6 January 2011). "How Studded Winter Tires May Damage Public Health, as Well as Pavement" . Retrieved 26 January 2011.
  8. ↑ Nordström, Olle (2004), "Nya och begagnade vinterdäcks isfriktion: sammanfattningsrapport : undersökning avseende inverkan av ålder, mönsterdjup, slitbanehårdhet, dubbutstick och dubbkraft", VTI Meddelande (in Swedish) (966), ISSN   0347-6049
  9. ↑ Gustafsson, M.; et al. (2006), Effekter av vinterdäck - en kunskapsöversikt, Väg-och transportforskningsinstitutet
  10. ↑ "Studded Tires for Winter Driving". Tirerack.com. Retrieved 24 January 2015.
  11. ↑ US Army, Stuttgart. "Winter Tire Rules" (PDF). stuttgart.army.mil. US Army. Retrieved 29 March 2017.
  12. ↑ Subcommittee: F09.20 (2016). "ASTM F1805 – 16: Standard Test Method for Single Wheel Driving Traction in a Straight Line on Snow- and Ice-Covered Surfaces". ASTM Book of Standards. 9 (2): 14. doi:10.1520/F1805-16 . Retrieved 26 March 2017.
  13. ↑ Department of Transportation (2007). §571.139 Standard 139 – New pneumatic radial tires for light vehicles. Vol. Title 49. Washington, DC: Office of Federal Register. p. 505. ISBN   9781577857778.
  14. 1 2 "冬のタイヤの滑り止めルールって？". Tire Fair Trade Council.
  15. ↑ "Snow Tires on Your Car: Not Just a Necessity But Sometimes a Law". 1816 – The Magazine. Remington. 16 January 2015.
  16. ↑ "チェーン規制について". Ministry of Land, Infrastructure, Transport and Tourism.
  17. 1 2 e-Gov Laws and Regulations Database (27 June 1990). "The Act on Prevention of the Generation of Spike Tire Dust (Act No. 55)". law.e-gov.go.jp/htmldata/H02/H02HO055.html. Government of Japan.
  18. ↑ "Winter Regulations—European regulations for winter equipment on trucks and buses". continental-tires.com. Continental Tires. 2016. Retrieved 26 March 2017.
  19. ↑ "Winter tyres legislation in Europe - An overview of the regulations | Uniroyal". www.uniroyal-tyres.com. Retrieved 23 July 2018.
  20. ↑ Brimborg ehf. (10 December 2017). "Winter driving in Iceland on winter tyres". Dollar Rent-a-Car Iceland.
  21. ↑ "Cooper Recalls 7,067 Discoverer M+S Sport Tires". moderntiredealer.com. Modern Tire Dealer. 21 February 2017. Retrieved 26 March 2017.
  22. ↑ "What You Should Know—Tires for Winter Driving". tracanada.ca. Tire and Rubber Association of Canada. Retrieved 26 March 2017.
  23. ↑ Dudley, David (6 December 2016). "The Joy and Terror of Urban Snow Driving". CityLab . Retrieved 13 December 2016.
  24. ↑ "Legislation for Snow Tires in the USA". bartecusa.com. Bartec USA LLC. 2017. Retrieved 26 March 2017.
  25. ↑ "Legislation for Snow Tires in Canada". bartecusa.com. Bartec USA LLC. 2017. Retrieved 26 March 2017.
  26. ↑ TranBC (2017). "Designated Winter Tire & Chain-up Routes". gov.bc.ca. Transport British Columbia. Archived from the original on 27 March 2017. Retrieved 26 March 2017.
  27. ↑ "National Parks Highway Traffic Regulations". justice.gc.ca. Government of Canada. 23 March 2017. Retrieved 26 March 2017.
  28. ↑ "Winter Preparation". saaq.gouv.qc.ca. SAAQ. 2019. Retrieved 9 November 2019. From 1 December to 15 March, your vehicle must be equipped with four winter tires that meet established standards and are in good condition.
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