All about studs for winter tires
In the novel by American science fiction writer Vernor Vinge, “Flames Over the Abyss, ” people find themselves on a planet inhabited by a race of dog-like intelligent creatures. One of the heroes of the book, having experienced fear of false spikes on the claws of soldiers, gives the race a very accurate nickname, symbolizing their power over the surrounding nature: “Steel Claws”. One can hardly find a figurative name that would better reflect the main function of studs - a very important part of studded winter tires.
Studs and VelcroIt is difficult to establish exactly when and who first thought of equipping car tires with spikes, but they appeared at the end of the 19th century. The first spikes were home-made, made from improvised materials - nails or self-tapping screws, but in the middle of the XX century in countries where a thick layer of snow and ice covers the ground in winter, they noticed the excellent coupling properties of studded tires. Since then, just such tires have become a peculiar winter standard in the Scandinavian countries, and only recently have they been pressed into the market by friction ("Velcro").
Both Velcro and studding have their own strengths and weaknesses that determine the choice of one or another type of tire. "Velcro" have an advantage at temperatures above zero, on dry and wet asphalt, and also are much more careful about the road surface, which makes them popular in large cities, where roads are regularly cleaned of snow and treated with anti-icing reagents. They are better even when the thermometer column drops below minus 20 Celsius - the ice becomes too hard, and the spikes can no longer catch on it. Both types of snow work approximately equally well on snow, but studded tires have a very serious advantage on smooth ice in moderate frost: thanks to the spikes that penetrate the ice, they have much better grip properties.
Tangle of contradictionsThe main problem is that the spikes must combine a number of very contradictory properties: they must not wear out quickly, otherwise the tire will lose its “ice” qualities, and should not wear out too slowly, because the tire tread is also erased. If the spike protrudes slightly over the tread, it will not be able to pierce the ice. If it protrudes too much, the likelihood of it falling out will increase. In addition, such a stud strongly destroys the road surface, therefore, legislative restrictions have been introduced on the height of the protruding stud (1.2 for new tires and 2? Mm for worn ones).
Evolution theoryIn order for the spike to satisfy all these conflicting requirements, it must have a composite structure: body (body) and pin (solid wear-resistant insert). Cases are single-flange, similar in shape to a nail, and two-flange (or multi-flange, but this is an exotic option). Two-flange are much better kept in the tire and fall out less during operation. In addition, the upper flange prevents water and dirt from entering the spike socket, which also contributes to durability and long service life.
Studs round in cross section are cheaper and easier to insert into tires (at the factory), but today manufacturers prefer to make studs directed: their insert is not round, but has a complex shape. Depending on the width and shape of the insert (it can be square, rectangular, rhomboid, oval, trapezoidal, etc.), you can optimize certain tire characteristics on ice - braking, handling, acceleration. If the insert is asymmetric, you need to correctly orient it relative to the direction of rotation of the tire when installing the stud, and also prevent further rotation of the stud in the seat, so the flange is not round for such studs either.
Twenty years ago, the stud body was made of steel, but now such studs can only be seen on trucks and buses. For passenger car tires, lighter aluminum stud housings are used, into which a tungsten carbide insert made by powder sintering is pressed. There were attempts to make studs made of plastic, but for various reasons (mainly due to low strength) they were abandoned.
The new regulation on studded tires, which entered into force in Scandinavia last year, limits the number of studs to 50 pieces per linear meter of tire circumference. But there is a loophole in the law: the number of spikes may be greater if the manufacturer demonstrates that the impact of such a tire on the road surface is below a certain level. The loophole has already been exploited by two major manufacturers - Nokian and Continental. The mass of one tenon is also limited to 1.1 g, so that the tenons become smaller and lighter. But the tenacity of new tires designed to meet these requirements, as shown by practical tests, it almost did not affect. After all, studs are only one, albeit quite important, element of tire construction. They do not work separately from the tire, but only together with all its elements. And of course, together with the main element that prevents accidents - the one that is between the steering wheel and the seat.
MichelinX-Ice North (2005) [RICH_HTML type = imageset] [/ RICH_HTML] Type: two-flange Material: aluminum Insert form: round
This first-generation model uses a classic double-flange spike with a circular cross section. The company's engineers felt that they needed exactly omnidirectional traction characteristics on ice, which are best provided by round spikes.
X-Ice North 2 (2009)
The second generation of tires is equipped with spikes of a slightly modified shape, but the general ideology remains the same: spikes with omnidirectional coupling characteristics complement what the tread provides.
X-Ice North 3 (2013)
The spikes of the third generation increased in size, and significantly, the shape of the upper flange also changed - now it is conical (and the cone is not inverse, but straight). But due to the sampling-deepening in the supporting lower flange, the mass of the spike remained the same (1.1 g) to comply with the new regulation. Due to the increase in the size of the lower flange, the spikes “sit” more firmly in the tire. A two-layer tread with a lower layer of thermoactive mixture helps to hold the spike (and “push” it if necessary).
ContinentalContiWinterViking (1999) [RICH_HTML type = imageset] [/ RICH_HTML] Type: two-flange Material: aluminum Insert form: round
Simple two-flange studs with a round insert were installed on an early modification of the first generation of this tire family. The release of this modification lasted four years.
ContiWinterViking 1 (2003)
The second modification of the tire bristled with modified spikes with an oval insert, oriented across the direction of travel. This form has improved the acceleration and braking characteristics on ice. To prevent the spike from rotating in the socket, two cuts were made on the lower flange.
ContiWinterViking 2 (2005)
The manufacturer gave such a romantic name to inserts with a rectangular section and a cut in the form of a “roof”. True, this cut is quickly erased during operation. The insert is oriented across the direction of travel. Two cuts of the lower flange prevented the rotation of the spike in the socket.
Due to the shape resembling a bone, the insert, according to the manufacturer, works more effectively in the transverse direction. In addition, these spikes are not just installed, but glued to the seat, as a result of which their loss during operation is minimal.
In connection with the introduction of new requirements in 2013, the manufacturer updated its flagship tire by changing the composition of the rubber compound and the design of the studs. New spikes (HD, Hybrid Dubb) are smaller and lighter than diamond studs (BD, Brilliant Plus Dubb). The insert has a smaller lateral size, and the geometry of the stud has changed, due to which the tires passed the test for wear of the road surface without reducing the number of studs.
NokianNordman 4 (2009) [RICH_HTML type = imageset] [/ RICH_HTML] Type: two-flange Material: aluminum Insert form: round
The model for the budget segment of the market is equipped with classic aluminum two-flange studs with a round insert (the Hakkapeliitta 2 model was equipped with the same).
Nordman 5 SUV (2014)
For new tires of the budget segment, studs with a square insert and square flanges are used, tested on the Hakkapeliitta 5 tire.
Hakkapeliitta 7 (2009)
In this generation, the insert has the shape of an elongated hexagon, oriented transversely to the direction of movement. To hold the spikes more firmly, the lower flange is enlarged.
Hakkapeliitta 8 (2013)
In an effort to comply with the new regulations, Nokian has taken an alternative path. The new aluminum tenon with a hexagonal insert is shorter and lighter (0.8 g) than the ten-generation tenon. Since this seriously reduces the impact on the road surface, the number of studs is not standardized.
GoodyearUltragrip 400 (1996) [RICH_HTML type = imageset] [/ RICH_HTML] Type: single-flange Material: steel Insert form: round
Spikes - “nails” - single-flange, with a round insert and a steel body. It was the latest generation of Goodyear single-flange studded winter stud tires.
Ultragrip 500 (2001)
In a tire that came out in 2001, a two-flange stud with a steel casing was used (although the upper flange was not much wider than the waist) and a regular round insert.
Ultragrip Extreme (2007)
The first modification of this tire came with a two-flange stud and a round insert, but the casing has already been replaced with aluminum, making the studs lighter.
Ultragrip Extreme (2010)
The hexagonal insert improved the grip of the tire, as sharp edges break ice better.
Ultragrip Ice Arctic (2012)
Today it is probably the most complex spike in shape. The long base of the trapezoidal insert has an arc shape. It is this arc that is responsible for traction with ice during braking, which significantly affects the reduction in stopping distance on ice. The short straight base of the trapezoid is responsible for traction during acceleration, and the beveled sides improve handling. For proper installation of the spike, the bottom flange is made triangular, and in the tire, the spike holds a special two-layer rubber "cover". Its lower layer of harder rubber reliably fixes the spikes, and the outer, softer, is responsible for the grip properties of the tire.
GislavedNord Frost 3 (2000) [RICH_HTML type = imageset] [/ RICH_HTML] Type: two-flange Material: aluminum Insert form: round
The previous version had very original spikes with a plastic case, but the manufacturer decided to return to more traditional ones.
Nord Frost 3 (2003)
In the second modification, the tires were equipped with spikes with an oval insert, oriented across the direction of movement, in order to increase acceleration and braking performance on ice.
Nord Frost 5 (2006)
Having missed one digit in the numbering of generations, the new tire model received spikes that are completely similar to those equipped with the ContiWinterViking 2 tires.
Nord Frost 100 (2013)
The number of spikes is limited, in accordance with the new regulation, to 50 pieces per linear meter. However, the spikes themselves are very interesting: the shape of the insert increases its effective lateral size, improving the grip of the tire. The stud body is round, the upper flange in the form of a reverse cone ("shot glass") holds the stud more firmly in the tire.
MatadorMP50 Sibir Ice (2012) [RICH_HTML type = imageset] [/ RICH_HTML] Type: two-flange Material: steel Insert form: round
The tire of the budget segment is equipped with a simple steel two-flange stud with a round insert.
CordiantSnow Cross (2013) [RICH_HTML type = imageset] [/ RICH_HTML] Type: two-flange Material: aluminum Insert form: round
Aluminum housing with a top flange in the form of a reverse cone ("shot glass") and a round insert. Snowflake-shaped grooves are applied on the upper end of the flange to complement the tire tread design. A two-layer tire tread with a lower, harder layer firmly holds the studs and prevents them from losing.The article “Steel Claws” was published in the journal Popular Mechanics (No. 10, October 2014).