![Bicycle tube](https://upload.wikimedia.org/wikipedia/commons/2/29/Bicycle_tube.jpg)
A bicycle tire is 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 ...
that fits on the
wheel
A wheel is a circular component that is intended to rotate on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machines. Wheels, in conjunction wi ...
of a
bicycle
A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist.
Bic ...
or similar vehicle. These tires may also be used on tricycles,
wheelchair
A wheelchair is a chair with wheels, used when walking is difficult or impossible due to illness, injury, problems related to old age, or disability. These can include spinal cord injuries ( paraplegia, hemiplegia, and quadriplegia), cerebr ...
s, and
handcycle
A handcycle is a type of human-powered land vehicle powered by the arms rather than the legs, as on a bicycle. Most handcycles are tricycle in form, with two coasting rear wheels and one steerable powered front wheel. Despite usually having th ...
s, frequently for
racing
In sport, racing is a competition of speed, in which competitors try to complete a given task in the shortest amount of time. Typically this involves traversing some distance, but it can be any other task involving speed to reach a specific goa ...
. Bicycle tires provide an important source of
suspension
Suspension or suspended may refer to:
Science and engineering
* Suspension (topology), in mathematics
* Suspension (dynamical systems), in mathematics
* Suspension of a ring, in mathematics
* Suspension (chemistry), small solid particles suspend ...
, generate the lateral forces necessary for
balancing and
turning
Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.
Usually the term "turning" is reserved for the generation of ...
, and generate the longitudinal forces necessary for
propulsion
Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...
and
braking
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 ...
. Although the use of a pneumatic tire greatly reduces
rolling resistance
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy nee ...
compared to the use of a rigid wheel or solid tire, the tires are still typically, the second largest source, after
wind resistance (air drag), of power consumption on a level road.
The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the
safety bicycle
A safety bicycle (or simply a safety) is a type of bicycle that became very popular beginning in the late 1880s as an alternative to the penny-farthing ("ordinary") and is now the most common type of bicycle. Early bicycles of this style were kno ...
.
Bicycle tires are also used on
unicycle
A unicycle is a vehicle that touches the ground with only one wheel. The most common variation has a bicycle frame, frame with a bicycle saddle, saddle, and has a human-powered vehicle, pedal-driven direct-drive mechanism, direct-drive. A two spee ...
s,
tricycle
A tricycle, sometimes abbreviated to trike, is a human-powered (or gasoline or electric motor powered or assisted, or gravity powered) three-wheeled vehicle.
Some tricycles, such as cycle rickshaws (for passenger transport) and freight trikes, ...
s,
quadracycle
A quadracycle is a four-wheeled human-powered land vehicle. It is also referred to as a quadricycle, quadcycle, pedal car or four-wheeled bicycle amongst other terms.
Quadracycles have been in use since 1853 and have grown into several famil ...
s,
tandem bicycle
A tandem bicycle or twin is a form of bicycle (occasionally a tricycle) designed to be ridden by more than one person. The term tandem refers to the seating arrangement (fore to aft, not side by side), not the number of riders. Patents relat ...
s,
hand cycles, bicycle trailers, and
trailer bike
A trailer bike (also known as a trailer cycle, and trademarked names such as Trailerbike, Trail-a-bike, Half wheeler or Tagalong) is a one-wheeled, or sometimes two-wheeled, bicycle trailer designed to carry one or more children in positions tha ...
s.
History
![Sezione cerchione bicicletta](https://upload.wikimedia.org/wikipedia/commons/1/10/Sezione_cerchione_bicicletta.svg)
The first bicycle "tires" were iron bands on the wooden wheels of
velocipedes
A velocipede () is a human-powered land vehicle with one or more wheels. The most common type of velocipede today is the bicycle.
The term was probably first coined by Karl von Drais in French as ''vélocipède'' for the French translation of ...
. These were followed by solid rubber tires on
penny-farthing
The penny-farthing, also known as a high wheel, high wheeler or ordinary, is an early type of bicycle. It was popular in the 1870s and 1880s, with its large front wheel providing high speeds (owing to its travelling a large distance for every r ...
s. The first patent for "rubberized wheels" was granted to
Clément Ader
Clément Ader (2 April 1841 – 3 May 1925) was a French inventor and engineer who was born near Toulouse in Muret, Haute-Garonne, and died in Toulouse. He is remembered primarily for his pioneering work in aviation. In 1870 he was also one of t ...
in 1868. In an attempt to soften the ride, rubber tires with a hollow core were also tried.
The first practical pneumatic tire was made by
John Boyd Dunlop
John Boyd Dunlop (5 February 1840 – 23 October 1921) was a Scottish-born inventor and veterinary surgeon who spent most of his career in Ireland. Familiar with making rubber devices, he invented the first practical pneumatic tyres for his c ...
in 1887 for his son's
bicycle
A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist.
Bic ...
, in an effort to prevent the
headache
Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches.
Headaches can occur as a result ...
s his son had while riding on rough roads. (Dunlop's patent was later declared invalid because of prior art by fellow Scot
Robert William Thomson
Robert William Thomson PRSSA FRSE (29 June 1822–8 March 1873), from Stonehaven, Scotland, was the inventor of the fountain pen and original inventor of the pneumatic tyre.
Life
He was born on 29 June 1822 in Stonehaven in the northeas ...
.) Dunlop is credited with "realizing rubber could withstand the wear and tear of being a tire while retaining its resilience". This led to the founding of
Dunlop Pneumatic Tyre Co. Ltd in 1889. By 1890, it began adding a tough canvas layer to the rubber to reduce punctures. Racers quickly adopted the pneumatic tire for the increase in speed and ride quality it enabled.
Finally, the detachable tire was introduced in 1891 by
Édouard Michelin. It was held on the rim with clamps, instead of glue, and could be removed to replace or patch the separate inner tube.
[
]
Attaching to the rim
Three main techniques for attaching a bicycle tire to a bicycle rim have been developed: ''clincher'', ''wired'' and ''tubular''. Clinchers originally did not have wire in the beads
A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under ...
and the shape of the bead interlocked with a flange on the rim, relying on air pressure to hold the tire bead in place. However, this type of tire is no longer in general use and the term ''clincher'' has transferred to the modern wired-on tire. For the remainder of this article, the modern use of the word ''clincher'' will be assumed.
In an attempt to provide the best attributes of both wired and tubular methods, tubular clinchers have also been offered.
Clincher
Most bicycle tires are clincher types for use with "clincher" rims. These tires have a steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
wire or Kevlar
Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s a ...
fiber bead
A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under ...
that interlocks with flange
A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...
s inside of the rim. A separate airtight inner tube enclosed by the 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 ...
supports the tire carcass and maintains the bead lock. An advantage of this system is that the inner tube can be easily accessed for a patch repair or replacement of the tube.
The ISO 5775-2 standard defines designations for bicycle rims. It distinguishes between
# Straight-side (SS) rims
# Crochet-type (C) rims
# Hooked-bead (HB) rims
Traditional wired-on rims were straight-sided. Various "hook" (also called "crochet") designs re-emerged in the 1970s to seat the tire bead
Tire bead is the term for the edge of a tire that sits on the wheel. Wheels for automobiles, bicycles, etc. are made with a small slot or groove into which the tire bead sits. When the tire is properly inflated, the air pressure within the tire ...
on the wheel rim
The rim is the "outer edge of a wheel, holding the tire". It makes up the outer circular design of the wheel on which the inside edge of the tire is mounted on vehicles such as automobiles. For example, on a bicycle wheel the rim is a large ...
and hold the tire in place, resulting in the modern clincher design. This allows higher () air pressures than was possible older wired-on tires. In these designs, it is the interlocking of the bead with the rim flanges, not the tight fit or resistance to stretching of the bead, that keeps the tire on the rim and retains the air pressure.
Some clincher tires can be used without tubes in a system which is referred to as tubeless. Typical tubeless tires have airtight sidewalls and beads which are designed to maximize the seal between the tyre and the wheel rim.
Tubular or sew-up
Some tires are torus
In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanar with the circle.
If the axis of revolution does not tou ...
-shaped and attached to tubular rims with adhesive. Tubular rims are designed with shallow circular cross-section beds in which the tires seat instead of being attached to rim flanges by tire beads as in clincher types.
Providing suspension
Adequate tire casing stiffness is necessary to support the rider, while softness and flexibility in the casing is desirable for cushioning. Most bicycle tires are pneumatic, the stiffness of the tires is easily controlled by controlling the air pressure inside of the tire. Airless tires utilize a semi solid sponge type elastomer
An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus and high failure strain compared with other materials. The term, a portmanteau of ''elastic p ...
material which eliminates air loss through punctures and air seepage.
Pneumatic tires
In a pneumatic tire, pressurized air is held inside either with a separate, relatively impermeable inner tube, or by the tire and rim, in a tubeless system. Pneumatic tires are superior in providing effective cushioning while keeping rolling resistance very low.
Tubed
A tubed tire has a separate inner tube
An inner tube is an inflatable ring that forms the interior of some pneumatic tires. The tube is inflated with a valve stem, and fits inside of the casing of the tire. The inflated inner tube provides structural support and suspension, while the ...
, made of butyl rubber
Butyl rubber, sometimes just called "butyl", is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for isobutylene isoprene rubber. Polyisobutylene, also known as "PIB" or polyisobutene, (C4H8)n, is the ho ...
or latex
Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well.
In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms ...
, that provides a relatively airtight barrier inside the tire. A vast majority of the tire systems in use are clinchers, due to the relative simplicity of repairs and wide availability of replacement inner tubes.
Most of bicycle inner tubes are torus
In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanar with the circle.
If the axis of revolution does not tou ...
-shaped balloons while some are not. For example, inner tubes in bicycles of the Moscow bike-sharing service are simply rubber tubes long enough to be coiled and inserted into a tire.
Tubeless
Tubeless tires are primarily used on 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 ...
s due to their ability to use low air pressure for better traction without getting pinch flats. Tubeless tires work similarly to clinchers in that the bead of the tire is specifically designed to interlock into a corresponding tubeless rim, but without an inner tube. Air is inflated directly into the tire, and once "locked" into the rim, the system is airtight. Liquid sealants are often injected into tubeless tires to improve sealing and to stop leaks caused by punctures. An advantage is that pinch flats are less common in a tubeless setup because they require a hole through the tire carcass, not just the inner tube. A disadvantage is that air can escape if the bead lock is compromised from too much lateral force on the tire or deformation of the rim/tire due to hard impact with an object.
Tubeless tires require tubeless-compatible rims, which do not allow air to escape where the spokes connect and have a different shape groove for the tire bead to seat.
=Road tubeless
=
In 2006, Shimano
, originally and later , is a Japanese multinational manufacturing company for cycling components, fishing tackles and rowing equipment, who also produced golf supplies until 2005 and snowboarding gear until 2008. Named after founder Shozaburo ...
and Hutchinson introduced a tubeless system for road bicycles. Tubeless tires have not yet gained popular acceptance in road racing due to lack of sponsorship, the tradition of using tubular tires
A tubular tyre, referred to as a tub in Britain, a sew-up in the US, a single in Australia, or just a tubular is a bicycle tyre that is stitched closed around the inner tube to form a torus. The combination is then glued (sometimes with two-side ...
and the fact that, even without the inner tube, the combined weight of tubeless rims and tires is more than top-of-the-line tubular tire wheelsets. Road tubeless is gaining popularity among riders for whom the benefits are worth the costs. Road tubeless tires tend to be a much tighter fit than traditional clincher tires, which makes mounting and removing the tire more difficult.
Airless tires
Airless were used before pneumatic tires were developed, appearing on velocipede
A velocipede () is a human-powered land vehicle with one or more wheels. The most common type of velocipede today is the bicycle.
The term was probably first coined by Karl von Drais in French as ''vélocipède'' for the French translation o ...
s by 1869. They continue to be developed in an effort to solve the problem of losing air pressure, either from a puncture or from permeability. Modern examples of airless tire
Airless tires, non-pneumatic tires (NPT), or flat-free tires are tires that are not supported by air pressure. They can be used on small vehicles such as riding lawn mowers and motorized golf carts. They also are used on heavy equipment require ...
s for bicycles include BriTek's Energy Return Wheel, an airless bicycle tire from 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 ...
,
the tire pictured to the right on a Mobike, and solid tires discussed below.
Although modern airless tires are better than early ones, most give a rough ride and may damage the wheel or bicycle.
Solid
The most common form of airless tire is simply the solid tire
Airless tires, non-pneumatic tires (NPT), or flat-free tires are tires that are not supported by air pressure. They can be used on small vehicles such as riding lawn mowers and motorized golf carts. They also are used on heavy equipment require ...
. Besides solid rubber, solid tires made of polyurethane
Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethan ...
or microcellular foam are also offered for 100% flat prevention. Much of the desirable suspension quality of the pneumatic tire is lost, however, and ride quality suffers.
Many bicycle-sharing system
A bicycle-sharing system, bike share program, public bicycle scheme, or public bike share (PBS) scheme, is a shared transport service where bicycles are available for shared use by individuals at low cost.
The programmes themselves include bot ...
s use these tires to reduce maintenance, and examples of solid tires include those available from Greentyre, Puncture Proof Tyres Ltd, KIK-Reifen, Tannus,[ Hutchinson, and Specialized.
]
Construction
Bicycle tires consist of a rubber-impregnated cloth
Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not the ...
casing, also called the carcass, with additional rubber, called the tread, on the surface that contacts the road. In the case of clinchers, the casing wraps around two beads, one on each edge.
Casing
Bicycle tire casing is made of cloth, usually nylon
Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic.
Nylon is a silk-like thermoplastic, generally made from petro ...
, though cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus ''Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor perce ...
and silk
Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...
have also been used. The casing provides the resistance against stretching necessary to contain the internal air pressure while remaining flexible enough to conform to the ground surface. The thread count
Textile fibers, threads, yarns and fabrics are measured in a multiplicity of units.
* A fiber, a single filament of natural material, such as cotton, linen or wool, or artificial material such as nylon, polyester, metal or mineral fiber, or man-m ...
of the cloth affects the weight and performance of the tire, and high thread counts improve ride quality and reduce rolling resistance at the expense of durability and puncture resistance.
Bias ply
The fibers of the cloth in most bicycle tires are not woven together, but kept in separate plies so that they can move more freely to reduce wear and rolling resistance. They are also usually oriented diagonally, forming bias plies.
Radial ply
Radial ply has been attempted, and examples include Panasonic in the 1980s and the Maxxis in the 2010s,[ but often found to provide undesirable handling characteristics.
]
Tread
The tread is the part of the tire that contacts the ground to provide grip and protect the casing from wear.
;Compound
The tread is made of natural
Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are p ...
and synthetic rubber
A synthetic rubber is an artificial elastomer. They are polymers synthesized from petroleum byproducts. About 32-million metric tons of rubbers are produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubbe ...
that often includes fillers such as carbon black
Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid ...
, which gives it its characteristic color, and silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
. The type and amount of filler is selected based on characteristics such as wear, traction (wet and dry), rolling resistance, and cost. Oils and lubricants may be added as softeners.[ ]Sulphur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
and zinc oxide
Zinc oxide is an inorganic compound with the formula . It is a white powder that is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, food supplements, rubbers, plastics, ceramics, glass, cemen ...
facilitate vulcanization
Vulcanization (British: Vulcanisation) is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include ...
.[ Some tires have a dual-compound tread that is tougher in the middle and grippier on the edges. Many modern tires are available with treads in a variety or combination of colors.] Road racing
Road racing is a form of motorsport racing held on a paved road surface. The races can be held either on a closed circuit or on a street circuit utilizing temporarily closed public roads. Originally, road races were held almost entirely on publ ...
tires with different tread compounds for the front and rear have been developed, thereby attempting to provide more traction in front and less rolling resistance in the rear.
;Pattern
Treads fall somewhere along the spectrum from smooth or slick to knobby. Smooth treads are intended for on-road use, where a tread pattern offers little to no improvement in traction. However, many otherwise slick tires have a light tread pattern, due to the common misbelief that a slick tire will be slippery in wet conditions. Knobby treads are intended for off-road use, where the tread texture can help improve traction on soft surfaces. Many treads are omnidirectional—the tire can be installed in either orientation—but some are unidirectional and designed to be oriented in a specific direction. Some tires, especially for 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 ...
s, have a tread which is intended either for the front wheel or the rear wheel. A special tread pattern, with small dimples
A dimple, also called a gelasin (, ) is a small natural indentation in the flesh on a part of the human body, most notably in the cheek. Numerous cultures believe that cheek dimples are a good luck charm that entices people who perceive them as ...
, has been developed to reduce air drag.
;Profile
The profile of the tread is usually circular, matching the shape of the casing inside it and allowing the tire to roll to the side as the bicycle leans for turning or balancing. More-squared profiles are sometimes used on mountain bike tires and novelty tires designed to look like automotive racing slicks, as on wheelie bike
A wheelie bike, also called a dragster, muscle bike, high-riser, spyder bike or banana bike, is a type of stylized children's bicycle designed in the 1960s to resemble a chopper motorcycle and characterized by ape hanger handlebars, a banan ...
s.
Bead
The bead of clincher tires must be made of a material that will stretch very little to prevent the tire from expanding off of the rim under internal air pressure.
;Wire
Steel wire beads are used on inexpensive tires. Though they cannot be folded, they can often be twisted into three smaller hoops.
;Kevlar
Kevlar beads are used on expensive tires, and these are also called "foldable". They should not be used on straight sidewall rims as they may blow off the rim.
Sidewall
The sidewall of the casing, the part not intended to contact the ground, may receive one of several treatments.
;Gum wall
Tires with sidewalls made of natural rubber are called "gum wall". The tan colored, natural rubber lacks carbon black to decrease rolling resistance, as its added wear resistance isn't needed in the sidewall.
;Skin wall
Tires with very little rubber, if any, covering the sidewall are called "skin wall". This reduces rolling resistance by reducing sidewall stiffness at the cost of reducing damage protection.
Variations
Puncture resistance
Some tires include an extra layer between the tread and the casing (as shown in the cross section pictured above) to help prevent punctures either by being tough or simply by being thick. These extra layers are usually associated with higher rolling resistance.
Studs
Metal studs may be embedded in the tread of knobby tires to improve traction on ice. Inexpensive studded tires use steel studs, while pricier tires use more durable carbide
In chemistry, a carbide usually describes a compound composed of carbon and a metal. In metallurgy, carbiding or carburizing is the process for producing carbide coatings on a metal piece.
Interstitial / Metallic carbides
The carbides of the ...
studs. A studded, knobby tread that zips onto a smoother, non-studded tire has been developed to ease the transition between the two types of tires.
Reflective
Some tires have a reflective strip on their sidewalls to improve visibility at night. Others have reflective material embedded in the tread.[
]
Aerodynamics
In addition to the dimple tread pattern mentioned above, at least one tire has an extra "wing" to cover the gap between the tire sidewall and the wheel rim and reduce drag.
Indoor use
At least one modern bicycle tire has been designed specifically for indoor use on rollers or trainers
Sneakers (also called trainers, athletic shoes, tennis shoes, gym shoes, kicks, sport shoes, flats, running shoes, or runners) are shoes primarily designed for sports or other forms of physical exercise, but which are now also widely used f ...
. It minimizes excessive wear that traditional tires experience in this environment and is not suitable for use on pavement.
Different front and rear
Besides the different tread patterns available on some mountain bike tires mentioned above, front and rear tire sets are available for road bikes with different tread patterns, tread compounds, and sizes for the front and rear wheels. Other scenarios involve replacing a damaged tire, and leaving the other one unchanged.
Self inflating
Bicycle tires have been developed that pump themselves up as they roll forward.
Modular
Bicycle tires have been developed so that different treads can be zipped on and off. This allows having the additional traction of studded tires
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 ...
only when necessary and avoiding the additional rolling resistance otherwise.
Parameters
Sizes
The modern tire-size designations (e.g. "37-622", also known as ETRTO) are defined by international standard ISO 5775
ISO 5775 is an international standard for labeling the size of bicycle tires and rims. The system used was originally developed by the European Tyre and Rim Technical Organisation (ETRTO). It is designed to make tire sizing consistent and clear. ...
, along with corresponding rim size designations (e.g., "622×19C"). Older English (inch, e.g. "28 × × ") and French (metric, e.g. "700×35C") designations are also still used, but can be ambiguous. The diameter of the tire must match the diameter of the rim, but the width of the tire only has to be in the range of widths appropriate for the width of the rim, while also not exceeding the clearances allowed by the frame, brakes, and any accessories such as fenders. Diameters vary from a large 910 mm, for touring unicycles, to a small 125 mm, for roller skiing
Roller skiing is an off-snow equivalent to cross-country skiing. Roller skis have wheels on their ends and are used on a hard surface, to emulate .Bryhn, Rolf and Knut Are Tvedt (eds.): ''Kunnskapsforlagets idrettsleksikon''. (Norwegian Encycloped ...
. Widths vary from a narrow 18 mm to a wide 119 mm for the Surly Big Fat Larry.
Lightweight tires
Lightweight tires range in size from wide.
Middleweight or Demi-balloon tires
Middleweight or Demi-balloon tires range in size from wide.
Balloon tires
A balloon tire is a type of wide, large-volume, low-pressure tire that first appeared on cruiser bicycle
A cruiser bicycle, also known as a beach cruiser or (formerly) motobike, is a bicycle that usually combines balloon tires, an upright seating posture, a single-speed drivetrain, and straightforward steel construction with expressive styling. ...
s in the US in the 1930s. They are typically wide.
In the 1960s Raleigh
Raleigh (; ) is the capital city of the state of North Carolina and the seat of Wake County in the United States. It is the second-most populous city in North Carolina, after Charlotte. Raleigh is the tenth-most populous city in the Southeas ...
made its small-wheeled RSW 16 with balloon tires[ www.bootiebike.com](_blank)
Raleigh RSW tyres - Retrieved February 25, 2017. so it would have a soft ride like the fully suspended Moulton Bicycle
Moulton is an English bicycle manufacturer based in Bradford-on-Avon, Wiltshire. The company was founded in 1962 by Alex Moulton (1920–2012) who had designed the "Hydrolastic" and rubber cone suspension systems for the BMC Mini motorcar. Mou ...
. Other manufacturers then used the same idea for their own small wheelers. Examples include the Stanningley
Stanningley is a district of Pudsey, West Yorkshire, England. It is situated approximately west of Leeds city centre on the A647 road, the original main road from Leeds to Bradford. The appropriate Leeds Metropolitan Ward is Bramley, Leeds, Bra ...
(UK)-made Bootie Folding Bicycle, the Co-operative Wholesale Society
A co-operative wholesale society, or CWS, is a form of co-operative federation (that is, a co-operative in which all the members are co-operatives), in this case, the members are usually consumer cooperatives. According to co-operative economi ...
(CWS) Commuter, and the Trusty Spacemaster.
Plus-size tires
A plus-size tire has a width of typically . Three bead seat diameters are available: 559 mm for 26+, 584 mm for 27.5+ (650B+), and 622 mm for 29+. They fill the gap between balloon and fat tires.
Fat tires
A fat tire is a type of wide oversized bicycle tire, typically or larger and rims or wider, designed for low ground pressure
Ground pressure is the pressure exerted on the ground by the tires or tracks of a motorized vehicle, and is one measure of its potential mobility, especially over soft ground. It also applies to the feet of a walking person or machine. Ground pre ...
to allow riding on soft unstable terrain, such as snow, sand, bogs, and mud.
Since the 1980s, fat tires of width , and diameters similar to conventional bicycle wheels, have been used on "fatbike
A fatbike (also called fat bike, fat tire, fat-tire bike, or snow bike) is an off-road bicycle with oversized tires, typically or larger and rims or wider, designed for low ground pressure to allow riding on soft, unstable terrain, such as snow ...
s" and all-terrain bikes designed for riding in snow and sand.
Inflation pressure
The inflation pressure of bicycle tires ranges from for fat bike
A fatbike (also called fat bike, fat tire, fat-tire bike, or snow bike) is an off-road bicycle with oversized tires, typically or larger and rims or wider, designed for low ground pressure to allow riding on soft, unstable terrain, such as sno ...
tires in snow to for tubular track racing tires.
The maximum pressure rating of tires is usually stamped on the sidewall, indicated as "Maximum Pressure", or "Inflate to ..." or sometimes expressed as a range like "". Decreasing pressure tends to increase traction and make the ride more comfortable while increasing pressure tends to make the ride more efficient and decreases the chances of getting pinch flats.
One published guideline for clincher inflation pressure is to pick the value for each wheel that produces a 15% reduction in the distance between the wheel rim and the ground when loaded (i.e. with the rider and cargo) compared to when unloaded. Pressures below this leads to increased rolling resistance and likelihood of pinch-flats. Pressures above this leads to less rolling resistance in the tire itself but to larger total energy dissipation
In thermodynamics, dissipation is the result of an irreversible process that takes place in homogeneous thermodynamic systems. In a dissipative process, energy (internal, bulk flow kinetic, or system potential) transforms from an initial form to ...
caused by passing vibrations to the bike and especially the rider, which experience elastic hysterisis.
Inner tubes are not completely impermeable to air and slowly lose pressure over time. Butyl inner tubes hold pressure better than latex. Tires inflated from carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
canisters (often used for roadside repairs) or helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
(occasionally used for elite track racing) lose pressure more quickly, because carbon dioxide, despite being a relatively large molecule, is slightly soluble in rubber, and helium is a very small atom which passes quickly through any porous material. At least one public bicycle sharing system
A bicycle-sharing system, bike share program, public bicycle scheme, or public bike share (PBS) scheme, is a shared transport service where bicycles are available for shared use by individuals at low cost.
The programmes themselves include bot ...
, London's Santander Cycles
Santander Cycles (formerly Barclays Cycle Hire) is a public bicycle hire scheme in London in the United Kingdom. The scheme's bicycles are popularly known as Boris Bikes, after Boris Johnson who was Mayor of London when the scheme began operati ...
, is inflating tires with nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, instead of simple air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
, which is already 78% nitrogen, in an attempt to keep the tires at the proper inflation pressure longer, though the effectiveness of this is debatable.
Effect of temperature
Since the volume of gas and the gas itself inside a tire is not altered significantly by a change of temperature, the ideal gas law
The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas. It is a good approximation of the behavior of many gases under many conditions, although it has several limitations. It was first stat ...
states that the pressure of the gas should be directly proportional to the absolute temperature
Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics.
Historically, thermodynamic temperature was defined by Kelvin in terms of a macroscopic relation between thermodynamic wor ...
. Thus, if a tire is inflated to at room temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
, , the pressure will increase to (+10%)
at and decrease to (-10%) at .
In the example above, a 7% difference in absolute temperature resulted in a 10% difference in tire pressure. This is a result of the difference between gauge pressure and absolute pressure. For low inflation pressures, this distinction is more important, as the ideal gas law applies to absolute pressure, including atmospheric pressure. For example, if a fat-bike tire is inflated to gauge pressure
Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressur ...
at room temperature and then the temperature is decreased to (a 9% decrease in absolute temperature), the absolute pressure of will be decreased by 9% to , which translates to a 30% decrease in gauge pressure, to .
Effect of atmospheric pressure
The net air pressure on the tire is the difference between the internal inflation pressure and the external atmospheric pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...
, , and most tire pressure gauges
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and ...
report this difference. If a tire is inflated to at sea level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
, the absolute internal pressure would be (+25%), and this is the pressure that the tire would need to contain if it were moved to a location with no atmospheric pressure, such as the vacuum of free space
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
. At the highest elevation of commercial air travel, , the atmospheric pressure is reduced to , and that same tire would have to contain (+20%).
Effect on carcass stress
Bicycle tires are essentially toroidal thin-walled pressure vessels and if the carcass is treated as a homogeneous
Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the uniformity of a substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, siz ...
and isotropic
Isotropy is uniformity in all orientations; it is derived . Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix ' or ', hence ''anisotropy''. ''Anisotropy'' is also used to describe ...
material then stress
Stress may refer to:
Science and medicine
* Stress (biology), an organism's response to a stressor such as an environmental condition
* Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...
in the ''toroidal'' direction (''longitudinal'' or ''axial'' stress if the tire is considered a long cylinder) can be calculated as:
:,
where:
* ''p'' is internal gauge pressure
* ''r'' is the inner, minor radius of the carcass
* ''t'' is thickness of the carcass
Stress in the ''poloidal'' direction (''hoop'' or ''circumferential'' stress if the tire is considered a long cylinder) is more complicated, varying around the minor circumference and depending on the ratio between the major and minor radii, but if the major radius is much larger than the minor radius, as on most bicycle tires where the major radius is measure in hundreds of mm and the minor radius is measured in tens of mm, then stress in the Poloidal direction is close to the hoop stress of cylindrical thin-walled pressure vessels:
:.
In reality, of course, the tire carcass is not homogeneous nor isotropic, but instead is a composite material
A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
with fibers imbedded in a rubber matrix, which complicates things further.
Rim width
While not strictly a tire parameter, the width of the rim on which any given tire is mounted has an influence on the size and shape of the contact patch, and possibly the rolling resistance and handling characteristics. The European Tyre and Rim Technical Organisation The European Tyre and Rim Technical Organisation (ETRTO) exists to specify and harmonise sizes of rims and their associated pneumatic tyres across the European Union. ETRTO sizes apply to rims and tyres for vehicles of all types, including bicycles ...
(ETRTO) publishes a guideline of recommended rim widths for different tire widths:
In 2006, it was expanded for allowing wide tires up to 50mm on 17C rims and 62mm on 19C rims.
Ideally, the tire width should be 1.8 to 2 times the rim width, but a ratio from 1.4 to 2.2 should fit, and even 3 for hooked rims.
Tire pressure versus width
Mavic recommends maximum pressures in addition to rim width, and Schwalbe recommends specific pressures:
Fatbike
A fatbike (also called fat bike, fat tire, fat-tire bike, or snow bike) is an off-road bicycle with oversized tires, typically or larger and rims or wider, designed for low ground pressure to allow riding on soft, unstable terrain, such as snow ...
tires of width are typically mounted on 65 to 100 mm rims.
Forces and moments generated
Bicycle tires generate forces and moments between the wheel rim and the pavement that can affect bicycle performance, stability, and handling.
Vertical force
The vertical force generated by a bicycle tire is approximately equal to the product of inflation pressure and contact patch area. In reality, it is usually slightly more than this because of the small but finite rigidity of the sidewalls.
The vertical stiffness, or spring rate
A spring is an elastic object that stores mechanical energy. In everyday use the term often refers to coil springs, but there are many different spring designs. Modern springs are typically manufactured from spring steel, although some non- ...
, of a bicycle tire, as with motorcycle and automobile tires, increases with inflation pressure.
Rolling resistance
Rolling resistance
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy nee ...
is a complex function of vertical load, inflation pressure, tire width, wheel diameter, the materials and methods used to construct the tire, roughness of the surface on which it rolls, and the speed at which it rolls.[ Rolling resistance coefficients may vary from 0.002 to 0.010,][ and have been found to increase with vertical load, surface roughness, and speed.][ Conversely, increased inflation pressure (up to a limit), wider tires (compared to narrower tires at the same pressure and of the same material and construction), larger-diameter wheels, thinner casing layers, and more-elastic tread material all tend to decrease rolling resistance.
For example, a study at the ]University of Oldenburg
The Carl von Ossietzky University of Oldenburg (german: Carl von Ossietzky Universität Oldenburg) is a university located in Oldenburg, Germany. It is one of the most important and highly regarded educational facilities in northwestern Germany ...
found that Schwalbe Standard GW HS 159 tires, all with a width of 47 mm and an inflation pressure of , but made for various diameter rims, had the following rolling resistances:
:
The author of the cited paper concludes, based on the data presented therein, that Crr is inversely proportional
In mathematics, two sequences of numbers, often experimental data, are proportional or directly proportional if their corresponding elements have a constant ratio, which is called the coefficient of proportionality or proportionality constan ...
to inflation pressure and to wheel diameter.
Although increasing inflation pressure tends to decrease rolling resistance because it reduces tire deformation, on rough surfaces increasing inflation pressure tends to increase the vibration experienced by the bicycle and rider, where that energy is dissipated in their less-than-perfectly-inelastic deformation. Thus, depending on the myriad of factors involved, increasing inflation pressure can lead to increasing total energy dissipation and either slower speed or higher energy consumption.
Cornering force and camber thrust
As with other pneumatic tires, bicycle tires generate cornering force
Cornering force or side force is the lateral (i.e., parallel to wheel axis) force produced by a vehicle tire during cornering.
Cornering force is generated by tire slip and is proportional to slip angle at low slip angles. The rate at which ...
that varies with slip angle
In vehicle dynamics, slip angle or sideslip angle is the angle between the direction in which a wheel is pointing and the direction in which it is actually traveling (i.e., the angle between the forward velocity vector v_x and the vector su ...
and camber thrust
Camber thrust and camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling tire due to its camber angle and finite contact patch. Camber thrust is generated when a point on the outer surface ...
that varies with camber angle
Camber angle is one of the angles made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of a wheel and the vertical axis of the vehicle when viewed from the front or rear. It is used in the design of steering an ...
. These forces have been measured by several researchers since the 1970s, and have been shown to influence bicycle stability.
Moments
Moments generated in the contact patch by a pneumatic tire include the self aligning torque
Self aligning torque, also known as aligning torque, aligning moment, SAT, or Mz, is the torque that a tire creates as it rolls along, which tends to steer it, i.e. rotate it around its vertical axis. In the presence of a non-zero slip angle, thi ...
associated with cornering force, twisting torque associated with camber thrust, both about a vertical axis, and an overturning moment about the roll axis of the bike.
Brands and manufacturing companies
*Bontrager
Keith Bontrager (; born December 18, 1954) is a motorcycle racer who became a pioneer in the development of the modern mountain bike. Between 1980 and 1995, he was president of his own Bontrager Company, which continues to develop components for ...
(owned by Trek)
*Cheng Shin Rubber
Cheng Shin Rubber Industry Co. () is a Taiwanese and the ninth largest tire company in the world. Established in 1967, in Yuanlin City, Changhua County, Taiwan, by Luo Jye
Luo Jye (; 1925 – 15 March 2019) was a Taiwanese billionaire, found ...
(also branded as Maxxis
Cheng Shin Rubber Industry Co. () is a Taiwanese and the ninth largest tire company in the world. Established in 1967, in Yuanlin City, Changhua County, Taiwan, by Luo Jye. Maxxis Tyres and CST tires are wholly owned subsidiaries of Cheng Shin.
...
and CST)
*Coker Tire
Coker Tire Company is a Chattanooga, Tennessee-based company that manufactures and sells vintage-style Michelin, Firestone, BF Goodrich and Uniroyal bias-ply and radial whitewall tires for collector automobiles. The company was originally a ...
*Continental
Continental may refer to:
Places
* Continent, the major landmasses of Earth
* Continental, Arizona, a small community in Pima County, Arizona, US
* Continental, Ohio, a small town in Putnam County, US
Arts and entertainment
* ''Continental'' ( ...
*Fyxation
Fyxation is a bicycle company based in Milwaukee, Wisconsin, founded by Nick and Ben Ginster in 2009. The initial products were pedals, handlebars, saddles, and tires. This has been expanded to include frames, complete bicycles, and leather beer a ...
* Hutchinson
*IRC Tire
Inoue Rubber Co., Ltd. is a Japanese maker of tires for bicycles, motorcycles, and wheelchairs and other rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of p ...
*Kenda
Kenda is a census town in the Jamuria CD block in the Asansol Sadar subdivision in the Paschim Bardhaman district in the Indian state of West Bengal.
Geography
Location
Kenda is located at . It has an average elevation of . The Asansol reg ...
*Maxxis
Cheng Shin Rubber Industry Co. () is a Taiwanese and the ninth largest tire company in the world. Established in 1967, in Yuanlin City, Changhua County, Taiwan, by Luo Jye. Maxxis Tyres and CST tires are wholly owned subsidiaries of Cheng Shin.
...
*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 ...
* Nokian (Now known as Suomi Tyres owned and manufactured by LieksaTyres Oy in Finland[Dunn & Bradstreet, March 25, 2022. https://www.dnb.com/business-directory/company-profiles.lieksatyres_oy.cc1eb91d2205c92dcb1c148018e35b48.html])
*Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation, headquartered in Kadoma, Osaka, Kadoma, Osaka P ...
* Schwalbe
*SOMA Fabrications
SOMA Fabrications is a designer and importer of bicycles, frames, parts and accessories based in the San Francisco Bay Area. It was established in 2001 and owned by bicycle parts wholesaler The Merry Sales Co.
The SOMA Fabrications brand came ab ...
*Specialized Bicycle Components
Specialized Bicycle Components, Inc., colloquially known as and stylized as SPECIALIZED, is an American company which designs, manufactures and markets bicycles, bicycle components and related products under the brand name "Specialized", as wel ...
* Suomi Tyres
* Vittoria
*Vredestein
Apollo Vredestein B.V. is a Netherlands-based tyre manufacturer. Since 2009, it is owned by Apollo Tyres Ltd of India. Apollo Vredestein has its head office in Amsterdam, Netherlands, and its production facility in Enschede. It designs, manufactur ...
*Wilderness Trail Bikes
Wilderness Trail Bikes (usually shortened to WTB) is a privately owned company based in Marin County, California, USA. Founded in 1982 as a company that specialized in mountain bike parts, today WTB sources and sells its product worldwide supplyi ...
See also
* Baisikeli Ugunduzi
Baisikeli Ugunduzi is a for-profit social business that specializes in bicycle components for the Sub-Saharan African market. ''Baisikeli Ugunduzi'' means innovative or modern bicycles in Swahili. It was founded in the winter of 2011 by Ben Mit ...
* Inner tube
An inner tube is an inflatable ring that forms the interior of some pneumatic tires. The tube is inflated with a valve stem, and fits inside of the casing of the tire. The inflated inner tube provides structural support and suspension, while the ...
* Outline of cycling
:''This article is an outline about the activity of cycling. For an outline about bicycles themselves, see outline of bicycles.''
:The following ''outline'' is provided as an overview of, as well as a topical guide to cycling:
Cycling, al ...
* Outline of tires
The following outline is provided as an overview of and topical guide to tires:
Tire (North American) or tyre (British) – ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by p ...
* Valve stem
A valve stem is a self-contained valve which opens to admit gas to a chamber (such as air to inflate a tire), and is then automatically closed and kept sealed by the pressure in the chamber, or a spring, or both, to prevent the gas from escaping ...
References
External links
Fix A Flat Tire
{{Bike equipment
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 ...
Tires