![Tire tread](https://upload.wikimedia.org/wikipedia/commons/9/9b/Tire_tread.jpg)
Siping is a process of cutting thin slits across a
rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...
surface to improve
traction in wet or icy conditions.
Siping was invented and patented in 1923 under the name of
John F. Sipe
John is a common English name and surname:
* John (given name)
* John (surname)
John may also refer to:
New Testament
Works
* Gospel of John, a title often shortened to John
* First Epistle of John, often shortened to 1 John
* Second E ...
. The story told on various websites is that, in the 1920s, Sipe worked in a
slaughterhouse
A slaughterhouse, also called abattoir (), is a facility where animals are slaughtered to provide food. Slaughterhouses supply meat, which then becomes the responsibility of a packaging facility.
Slaughterhouses that produce meat that is no ...
and grew tired of slipping on the wet floors. He found that cutting slits in the tread on the bottoms of his
shoe
A shoe is an item of footwear intended to protect and comfort the human foot. They are often worn with a sock. Shoes are also used as an item of decoration and fashion. The design of shoes has varied enormously through time and from culture t ...
s provided better traction than the uncut tread. Another story is that he was a deckhand and wanted to avoid slipping on a wet deck.
Tires
John Sipe's invention was unsuccessful. It was applied to solid rubber tires, rather than pneumatic tires, and so the tires had poor wet grip anyway, owing to their limited
contact patch
Contact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is commonly used in the discussion of pneumatic (i.e. pressurized) tires, where the term is used strictly to describe the portion of the tire’s ...
. It was his son, Harry E. Sipe, who popularised the use of sipes in the USA for the new low-pressure
balloon tire
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 ...
s around 1939.
The process was not applied to vehicle
tire
A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineering), t ...
s on a large scale until the 1950s, when superior tread compounds were developed that could stand up to the siping process. On roads covered with snow, ice, mud, and water, sipes usually increase traction. A US patent to Goodyear also claimed sipes improve tire traction, and tend to close completely in the tire "footprint" on the road. A 1978 study by the US
National Safety Council
The National Safety Council (NSC) is a 501(c)(3) nonprofit, public service organization promoting health and safety in the United States. Headquartered in Itasca, Illinois, NSC is a member organization, founded in 1913 and granted a congressi ...
found siping improved stopping distances by 22 percent, breakaway traction by 65 percent, and rolling traction by 28 percent ''on glare ice''. Since then, the council has retracted that study and is "not currently recommending or endorsing the siping procedure".
Tire tread block shapes, groove configurations, and sipes affect tire noise pattern and traction characteristics. Typically, wide, straight grooves have a low noise level and good water removal. More lateral grooves usually increase traction. Sipes are small grooves that are cut across larger tread elements. Up to a point, more sipes give more traction in snow or mud.
As is often the case, there are compromises.
Winter tire
Winter is the coldest season of the year in polar and temperate climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Different cultures ...
s, and "mud and snow" tires, may have thousands of sipes and give good traction. But, they may feel "squirmy" on a warm, dry road.
Unpatterned racing "slicks" on dry roads give maximum traction. These have no sipes, no grooves, and no tread blocks. However, they have very poor traction on even slightly wet surfaces. Tire manufacturers use different tread rubber compounds and tread designs for different tires' usages.
Large sipes are usually built into the tread during manufacturing. Sipes may also be cut into the tread at a later date, called "microsiping".
Bandag developed a machine for microsiping which places a curved knife blade at a slight angle on a rotating drum. The drum is placed so when it is pressed against the tread the tire is pressed into an exaggerated hollow, as if driving down a rail. The drum is lubricated and rotated and the knife makes a series of diagonal cuts across the tread. For improved traction, the tire may be siped twice, leaving diamond-shaped blocks. A significant problem with field siping is that the tread picks up rocks, glass, and other hard
road debris
Road debris, a form of road hazard, is debris on or off a road. Road debris includes substances, materials, and objects that are foreign to the normal roadway environment. Debris may be produced by vehicular or non-vehicular sources, but in all ...
in use, and even with thorough cleaning the knife service life is often poor.
Microsiping can dramatically improve tire traction in rain and snow. However, microsiped tires may also have increased road noise and tire wear when operated on dry surfaces. ''
Consumer Reports
Consumer Reports (CR), formerly Consumers Union (CU), is an American nonprofit consumer organization dedicated to independent product testing, investigative journalism, consumer-oriented research, public education, and consumer advocacy.
Founded ...
'' recommends against adding more than "the sipes that your tires come with" because of longevity and dry performance. Some companies such as
Les Schwab
Leslie Bishop Schwab (October 3, 1917 – May 18, 2007) was an American businessman from Oregon. He was the founder of Les Schwab Tire Centers, a company which ''Modern Tire Dealer'' called "arguably the most respected independent tire store chain ...
claim that microsiped tires reduce tire friction heat and tire wear and extends the life of the tire.
Both
Bridgestone
is a Japanese multinational tire manufacturer founded in 1931 by Shojiro Ishibashi (1889–1976) in the city of Kurume, Fukuoka, Japan. The name Bridgestone comes from a calque translation and transposition of , meaning 'stone bridge' in Japan ...
and
Michelin
Michelin (; ; full name: ) is a French multinational tyre manufacturing company based in Clermont-Ferrand in the Auvergne-Rhône-Alpes ''région'' of France. It is the second largest tyre manufacturer in the world behind Bridgestone and la ...
sell
snow tire
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 wi ...
s that are siped at the factory, while
Saf-Tee Siping and Grooving sells machines that can sipe most standard vehicle tires. Siping can also be done by hand. Siping tires may void the manufacturer's warranty. Claims that extended life is achieved by siping may only apply to certain environments,
operating temperature
An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the de ...
s, and rubber compound builds.
Use in racing tires
![BillyBoatMay2007](https://upload.wikimedia.org/wikipedia/commons/8/82/BillyBoatMay2007.jpg)
Fine slits are cut into the tire with a narrow blade, not near the size of a groove.
Racing tires are siped to increase speed.
The increased traction allows better contact to the dirt racing surface for increased braking, acceleration, and turning.
The sipes allow the tire to heat quicker at the start of their use and cool quicker.
Boat shoes
Siped
soles are a characteristic feature of
boat shoes
Boat shoes (also known as deck shoes) are typically canvas or leather with non-marking rubber soles designed for use on a boat. A siping pattern is cut into the soles to provide grip on a wet deck; the leather construction, along with the applic ...
.
References
{{Tires, state=collapsed
Tires
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