The tread of a

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 ...

track Track or Tracks may refer to: Routes or imprints * Ancient trackway, any track or trail whose origin is lost in antiquity * Animal track, imprints left on surfaces that an animal walks across * Desire path, a line worn by people taking the shorte ...

refers to the

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 ...

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

retread Retread, also known as "recap", or a "remold" is a re-manufacturing process for tires that replace the tread on worn tires. Retreading is applied to casings of spent tires that have been inspected and repaired. It preserves about 90% of the mat ...

ed. The word tread is often used casually to refer to the pattern of grooves molded into the rubber, but those grooves are correctly called the tread pattern, or simply the pattern. The grooves are not the tread, they are in the tread. This distinction is especially significant in the case of racing slicks, which have much tread but no grooves.

Tires

Street tires

The grooves in the rubber are designed to allow water to be expelled from beneath the tire and prevent

hydroplaning 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 fr ...

. The proportion of rubber to air space on the road surface directly affects its traction. Design of tire tread has an effect upon noise generated, especially at freeway speeds. Generally there is a tradeoff of tread friction capability; deeper patterns often enhance safety, but simpler designs are less costly to produce and actually may afford some

roadway A carriageway (British English) or roadway (North American English) consists of a width of road on which a vehicle is not restricted by any physical barriers or separation to move laterally. A carriageway generally consists of a number of tra ...

noise mitigation Noise control or noise mitigation is a set of strategies to reduce noise pollution or to reduce the impact of that noise, whether outdoors or indoors. Overview The main areas of noise mitigation or abatement are: transportation noise control, ...

. Tires intended for dry weather use will be designed with minimal pattern to increase the

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 ...

. Tires with a smooth tread (i.e., having no tread pattern) are known as

slicks 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 tr ...

and are generally used for racing only, since they are quite dangerous if the road surface is wet. Street tires will also include wear limit indicators in the form of small raised bridges within the grooves. When the tread is worn down enough that the limit indicators make contact with the road, the tire is deemed to be at the end of its service life.

Brake A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. Background ...

pads use similar indicators in the form of notches on their surface that disappear when they are used.

Snow tires

Snow tires or Winter tires are tires designed for use in colder weather, snow and ice. To improve traction, they are made of different rubber and have a different tread pattern from regular street tires.

Off-road tires

Off-road tire Off-road tires (Off-road tyre) 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 ...

s used in mud or dirt feature individual knob patterns to allow the tire to bite into the surface and lever the sides of the tread to get a better grip. Given the smaller contact patch, these tires tend to wear quickly when used on asphalt (depending on type of rubber).

Mountain bike and motorcycle tires

Mountain bike A mountain bike (MTB) or mountain bicycle is a bicycle designed for off-road cycling. Mountain bikes share some similarities with other bicycles, but incorporate features designed to enhance durability and performance in rough terrain, which ...

and some

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

tires feature tread similar to off-road tires used on cars and trucks but may sometimes include an unbroken tread that runs along its center. This feature provides better traction and lower noise on asphalt at high speed and on high tire pressure, but retains the ability to provide grip on a soft or loose surface- lower tire pressure or soft ground will cause the side lugs to come into contact with the surface. Road bike tires may have shallow grooves for aesthetic purposes, but such grooves are unnecessary in narrow applications.

Continuous tracks

Continuous track Continuous track is a system of vehicle propulsion used in tracked vehicles, running on a continuous band of treads or track plates driven by two or more wheels. The large surface area of the tracks distributes the weight of the vehicle b ...

s such as those used on military

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful engin ...

s or construction machines (i.e. caterpillar tracks) have metal track segments which may be rubber-coated. They usually do not feature tread patterns, because these would offer little additional grip given the weight of the tracked vehicle. Traction is usually provided by

grouser Grousers are devices intended to increase the traction of continuous tracks, especially in loose material such as soil or snow. This is done by increasing contact with the ground with protrusions, similar to conventional tire treads, and analog ...

s instead.

References

{{Powertrain Tires