Snow tires - also called winter tires - are tires designed for use on snow and ice. Snow tires have a tread design with a gap larger than the summer tires, increasing the attraction on snow and ice. The tire that has passed the special winter traction performance test is entitled to display the symbol "Three Peaks of Snowflake Mountain" on the side wall. Tires designed for winter conditions are optimized for driving at temperatures below 7 ° C (45 ° F). Some snow tires have metal or ceramic buttons protruding from tires to increase the grip on snow or hard ice. Studs scrape dry pavements, cause dust and create wear in the wheel lanes. Regulations requiring the use of snow tires or permitting the use of buttons vary by country in Asia and Europe, and by states or provinces in North America.
Related to the snowballs are those who have the M S rating, which show "throughout the season" ability - quieter in clear streets, but less capable of snow or ice than winter tires.
Video Snow tire
Highway conditions in winter
Snow tires operate on various surfaces, including sidewalks (wet or dry), mud, ice, or snow. The tread design of the snow tread is adjusted primarily to allow the penetration of snow into the tread, where it solidifies and provides resistance to slippage. The strength of the snow developed by compaction depends on the properties of the snow, which depends on the temperature and the water content - wetter, warmer snow solids better than dry, cooler snow to the point where the snow is so wet that it lubricates the tire. Road-interface. New snow and powders have a density of 0.1 to 0.3 g/cm 3 (6 to 20 lb/cuÃ, ft). Solid snow may have a density of 0.45 to 0.75 g/cm 3 (28 to 47 pounds/feet).
Snow-covered or ice-covered roads bring lower friction and cornering frictions, compared to dry conditions. The nature of road friction from the snow, in particular, is a function of temperature. At temperatures below -7 ° C (20 ° F), the snow crystal is harder and produces more friction as the tire passes over it than in warmer conditions with snow or ice on the road surface. However, when temperatures rise above -2Ã, Â ° C (28Ã, Â ° F), the presence of free water further lubricates snow or ice and reduces tire friction. Hydrophilic rubber compounds help create friction in the presence of water or ice.
- Dry and damp snow conditions on the highway
Maps Snow tire
Treads
The distinguishing attributes of "all-season" snow tires and summer tires include:
- The open and deep footprint, which is void ratio between the rubber and the distance between the solid rubber is relatively high
- Shoulder Block - special tread design on the outside of the tire tread to improve snow and friction contact
- Narrow aspect ratio between tire diameter and footprint width to minimize resistance from tire plowing effect through deeper snow
- Hydrophilic rubber compounds that increase friction on wet surfaces
Snow tires are designed to deal with many of the same conditions as summer tires, too, so they combine siping for a wet surface. Wet film conditions on snow or ice that are hard to compact require buttons or chains.
Studs
Many jurisdictions in Asia, Europe and North America are seasonally allowing snow tires with metal or ceramic buttons to increase the grip on snow or packed ice. Such tires are prohibited in other jurisdictions or during warmer months because of possible damage to the road surface. The metal buttons are made by wrapping hard pins in a softer base, sometimes called a jacket . Pin is often made from tungsten carbide, high performance ceramic that is very hard. The softer base is the part that clips the stud on the rubber tire. When the tire is worn, a softer base is worn so that the surface is almost the same as the rubber, while the hard pin is worn so that it protrudes from the tire. Pin should stand at least 1 millimeter (0.04 inches) in order for the tire to function properly. Snow tires do not eliminate skid in ice and snow, but they greatly reduce the risk.
The studdable tire is produced with a hole formed on the rubber tire footprint. Typically, there are 80 to 100 holes formed per tire for male insertion. The insertion is made using a special tool that spreads the rubber hole so that the stud jacket can be inserted and the flange at the bottom of the jacket can be securely attached to the bottom of the hole. The metal button has a certain height to adjust the depth of the hole formed to the tire footprint based on the depth of the tread. For this reason, the stud metal can only be inserted when the tire has not been moved. The correct insertion of stud studs in a flat metal jacket with the tire tread surface has only a prominent pin portion.
When the buttons touch the sidewalk, they erode the surface of the asphalt or concrete. This can cause contamination of dust and wear on wheel lanes that prevent proper drainage. For this reason, studded tires are banned, at least seasonally, in many jurisdictions.
Snow-tire
The compacted snow develops a force against the slip along the plane of the shear parallel to the tire contact field on the ground. At the same time, the underside of the tire tread compacts the snow into its cushion, also creating friction. The snow compaction process in the tread requires that it be thrown in time for the footprint to match new snow to the next rotation. The compaction process works well in the direction of travel for propulsion and braking, but also laterally for cornering.
The deeper the snow is rolled up the tire, the higher the obstacle encountered by the tire, because it compacts the snow it encounters and plows part to the other side. At a certain point at a certain angle of the uphill field, this resistance becomes larger than the resistance to the slippage achieved by the tread contact with the snow and the tire with the power begin to slip and rotate. Deeper snow means climbing the hill without turning the powered wheels becomes more difficult. However, the hijacking/compacting effect helps braking as far as it creates rolling resistance.
- Snow-snow interaction
Rule
ASTM International (ASTM International) is an international standards organization that develops and publishes voluntary consensus technical standards for various materials, products, systems and services. The relevant standards for snow tires are ASTM F1805-16, Standard Test Method for Single-Wheel Driving Traction in Straight Line on Closed Surface Snow and Ice, which assesses tire performance on snow and ice. It measures the traction of the tire under acceleration in a revolving direction. Tires passing this test are eligible to display the 3PMSF (Three Summits of Snowflake Mountain). Asia
In Russia light vehicles and buses must be fitted with M S or 3PMSF snow tires on all axles from December to February and have a minimum 4 millimeter (0.2 inches) tread depth.
All Japanese prefectures, except southern Okinawa prefecture, require motor vehicles to be fitted with winter tires or tire chains if the road is cold or slippery. If the tread groove has faded more than 50% of the original depth, the tire should be replaced to meet legal requirements. The driver will be fined for failing to meet the requirements of the snow tire or tire chain. The restriction of national-studded tires for passenger vehicles came into force in April 1991, followed by restrictions for commercial trucks in 1993. Ban studded is technically still legal in Japan, but its use is limited by environmental laws and is a criminal offense to operate vehicles equipped with sprinkled tires on dry asphalt or concrete.
Europe
By 2016, European regulations related to snow tires vary by country. The main aspect of the regulation is whether the use is mandatory and whether the studded tire is permitted.
- Mandatory use - The following countries require snow tires between specified dates : Austria, Bosnia-Herzegovina, Croatia, Czech Republic, Estonia, Finland, Germany, Latvia, Lithuania, Montenegro, Norway, Serbia, Slovakia, Slovenia, Sweden, and Russia.
- Ban-banned ban - The following countries forbid the use of studded tires: Albania, Belgium, Bosnia-Herzegovina, Bulgaria, Croatia, Czech Republic, Germany, Hungary, Luxembourg , Macedonia, Montenegro, The Netherlands, Poland, Portugal, Romania, Serbia, Slovakia, and Slovenia.
- Limited-studded tire - The following allows the use of seasonally-sprinkled tires: Austria, Denmark, Estonia, Finland, France, England, Iceland, Ireland, Latvia, Lithuania, Norway, Russia, Spain, Sweden, and Switzerland.
North America
The US National Highway Traffic Safety Administration (NHTSA) and Transport Canada allows the display of the 3PMSF symbol to show that the tire has exceeded the industry requirements of a non-snow reference tire. By 2016, snow tires are 3.6% of the US market and 35% of the Canadian market.
The US and Canadian provinces control the use of snow tires. No state or province (except Quebec) requires snow tires. They may need snow tires or chains only in certain areas during the winter:
- British Columbia - Snow tires are only required by law in certain "winter paths & chain amps" defined in mountain areas. In this area, motorists must use winter tires or carry a tire chain. Alberta - Banff National Park or Jasper National Park requires a car to have a snow tire or tire chain between 1 November to 31 March, or another period where the road is covered with snow or ice.
- Quebec - Winter tires or studded tires should be used from 15 December to 15 March.
The use of studded tires is set in the United States and Canada by each state and province, as follows:
- Unlimited is used - The following jurisdictions allow unlimited use of studded snow tires; US : Colorado, Kentucky, North Carolina, Vermont, and Wyoming; Canada : Alberta, Northwest Territories, Saskatchewan, and Yukon
- Prohibited - Striped snow tires can not be used in Hawaii, Mississippi, or Puerto Rico.
- Seasonal is used - All other states and provinces allow seasonal use of studded snow tires. In Alabama, Florida, Louisiana, Michigan, and Texas, only rubber buttons are allowed.
References
Source of the article : Wikipedia
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