A flat tire (British English: flat tyre) is a deflated pneumatic tire, which can cause the rim of the wheel to ride on the tire tread or the ground potentially resulting in loss of control of the vehicle or irreparable damage to the tire. The most common cause of a flat tire is puncturing of the tire by a sharp object, such as a nail or pin, letting the air escape. Depending on the size of the puncture, the tire may deflate slowly or rapidly.[1]
A flat tire in a busy district in Lagos, Nigeria. A vehicle with a flat tire can cause local delays in traffic.
Other causes
Besides puncturing of the tire a flat can be caused by: failure of or damage to the valve stem; a nail in the tire; rubbing of the tire against the road; ripping of the tire; separation of tire and rim by collision with another object; excessive wear of the tire tread allowing explosive tire failure or road debris tearing through the tire.
Some tyres, particularly those with a slow leak, can be repaired and re-inflated; others, especially those with worn tread, must be replaced.
Driving or riding with a flat tire
Where a flat tire occurs, drivers are advised to slow gradually and pull off the road.[2] Continuing to drive may damage the wheel, the hub or other parts of the vehicle. Driving with a flat tire, especially at high speeds, may result in a loss of control and possibly result in a car accident.
On a bicycle, a flat tire will compromise handling, as well as increasing rolling resistance.
Motor vehicles are normally equipped for changing a tire. These tools include a jack, a tire iron or lug wrench, and a spare tire. Air pumps run by hand-lever, pressure cans, or electricity can be used to re-inflate slow-leaking tires.
One common way to temporarily repair and re-inflate a punctured tire at the roadside is to use a canned tire sealant. The motorist attaches this to the valve, and the compressed propellant inside forces the can's contents through the valve into the tire, a liquid sealant is forced towards the puncture and will seal the puncture. The compressed propellant also inflates the tire. Tire sealant is typically useful on punctures of 3/16in. (5mm) diameter or less. According to research carried out by Continental Tires, 95% of punctures are caused by objects of 5mm or less. Typically, the sealant is a water-based latex solution that can easily be removed by a tire repair professional before a permanent repair is made. Canned tire sealants are quick and simple to use and have the added benefit of working when the vehicle is in a dangerous location such as at the side of a busy highway, or on uneven ground.
A flat tire on an Fiat Panda automobileA roadside tire repair shop in Niger, West-Africa
A water-based sealant can be injected into the tire also through the valve stem. This contains less harmful chemicals and no aerosol gas. The sealant can then be driven into the tire using an air compressor.
A flat tire can be repaired by a patch or plug;[4] or the tire may repair itself. Self-sealing tires work on punctures up to a certain size.
Patch repair is commonly used in a repair shop. Some may not patch a worn tire if: the hole is close to a previous patch; there are already more than two patches; the puncture requires more than two patches; the punctures are too close, and/or the puncture is close to the sidewall. A patch is performed by removing the tire, marking the puncture, scouring the surface to create a smooth surface (inside of the tire), applying rubber cement, applying the patch, then pressing it into the surface with a small metal wheel attached to a handle. An alternative is a combination patch and plug. This is manufactured with a plug built into it; applying this patch is done similarly except with more steps, including drilling a hole at the puncture so the plug can be pulled through it, as well as cutting off the excess plug from the outside the tire.
The final method, the tire plug, can be performed without removing the tire. The penetrating object is removed from the tire, and a plug coated in rubber cement then inserted with a handle, typically supplied with the kit. Many technicians consider plugs less reliable than patching though more reliable than sealant.
One disadvantage of patching a tire is that due to the process requiring one to remove the tire from the wheel, the tire must be balanced again when it is put back on the wheel. Tire sealant also creates an imbalance in the tire, but since it is a temporary repair, it is considered less of an issue. However, the issue of disposal of the tire sealant, the hazards to the technician, as well as the required cleaning of both the inside of the tire as well as the wheel could all be considered disadvantages of tire sealant.
Tires can leak air for a variety of reasons. These include, but are not limited to: damage to the wheel itself, a damaged valve stem, a puncture in the tire (which can be hard to find if the puncturing object didn't embed itself in the tire) and improper installation of the tire, which could involve the bead of the tire being cut when installed with excessive force.
Occasionally, a puncture may not "go all the way through" to the inside of the tire. Thus, before coming to the conclusion that a puncture is causing air to leak from the tire, attempt to remove the puncture lightly by hand. It's very possible that the head of a nail or a very short nail created the appearance of a puncture, while not actually being one.
Also worth mentioning is the fact that tires simply lose air over time. A brand new tire, properly inflated, will lose air even with no punctures present. This is mainly due to the design of the valve stem, among other reasons. Given enough time, a tire can fully deflate with no outside intervention.
Thin-walled tires, especially those used in road racing bicycles, are particularly susceptible to puncture by road debris, such as thorns, and small pieces of glass that would not affect tires with more substantial tread. The equipment needed to repair or replace a bicycle inner tube is comparatively minimal, and frequently carried by cyclists.
On the road, the easiest approach to dealing with a flat tire, should a spare inner tube be available, is to replace the tube. The wheel is removed, the tire levered from the rim and inspected for causes of damage, and the inner tube replaced and wheel inflated. Re-inflation can be carried out by the use of a frame mounted pump or a CO2 cartridge inflator. The CO2 cartridge is generally a single use item only while the pump can be used to inflate many flat tires. The inner tube may then be repaired at a later date.
Puncture repair kit, complete with tire levers, vulcanizing fluid, abrasive grater and fabric, puncture patches, and a bit of chalk to mark the puncture
The repair of inner tubes may be necessary on the road. Several methods exist to locate a small puncture, including submersion in water with dish soap, but without a bowl of water available, the simplest method may be to inflate the tube until air can be felt escaping from the puncture. Once located, the puncture is cleaned, and a patch applied (see Louis Rustin for the invention of the puncture patch). Note that tire valves may also become damaged. In this case, repair of the inner tube will not be possible, and the tube should be replaced.
Should damage to the tread of the outer tire be substantial, a tough, self-adhesive patch, known as a boot may additionally be placed inside the tire. Folded paper currency is frequently used as a makeshift boot by cyclists in need.
Racing bicycles frequently use tubular tires, which are glued to a special, flat wheel rim. The use of these is often restricted to circumstances where a full spare wheel is available.
Another approach to preventing punctures of lightweight tires is to use kevlar belts in the tire tread construction.
Another approach to preventing punctures in bicycle and other tires in general is the use of Slime, a proprietary brand of injectable liquid thick chemical goo.[citation needed] This chemical "goo" has a tendency to stick to, and coat the outer wall of the inner tube or tire, thus adding another layer of flexible rubber-type protection on the inside of the inner tube or tire. Many MTB riders, or "Mountain Bike Riders", further pre-treat their tires to prevent serious punctures or to prevent punctures in the first place. There are other brands of this same type of liquid, either in an unpressurized container or pressurized container with inflatable gas which is sold in many auto and bicycle stores. The auto sales version of this Fix-A-Flat type of chemical is sold in America.[citation needed]
Dangers of changing a flat tire
Motorists stranded by a flat tire face a number of hazards.
The most common hazard is from the passing traffic.[citation needed] Especially if the tire is on the side closer to the road, the motorist is at risk of getting hit by a passing car. If the motorist is unable to pull over to a place where the tire being changed is on the opposite side from the moving traffic, he may be directly in the path of or just inches away from passing cars. Even if some type of warning is placed on the road, a motorist not fully attentive may not be able to avoid the situation.
Some motorists, especially those with less physical strength, may risk injury while attempting to change a tire. Often, lug nuts are bolted very tightly to the wheel, and tires themselves are quite heavy.
While the use of a run-flat tire can prevent these problems, some run-flat tires have other inherent flaws that make them less appealing.
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
A bicycle pump is a type of positive-displacement air pump specifically designed for inflating bicycle tires. It has a connection or adapter for use with one or both of the two most common types of valves used on bicycles, Schrader or Presta. A third type of valve called the Dunlop valve exists, but tubes with these valves can be filled using a Presta pump.
A valve stem is a self-contained valve that opens to admit gas to a chamber, 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.
A cyclo-cross bike or cyclo-cross bicycle is a bicycle specifically designed for the rigors of a cyclo-cross race. Cyclo-cross bicycles roughly resemble the racing bicycles used in road racing. The major differences between the two are the frame geometry, and the wider clearances that cyclo-cross bikes have for their larger tires and mud and other debris that they accumulate.
The Presta valve is a tire valve commonly found in high pressure road style and some mountain bicycle inner tubes. It comprises an outer valve stem and an inner valve body. A lock nut to secure the stem at the wheel rim and a valve cap may also be present.
A beadlock or bead lock is a mechanical device that secures the bead of a tire to the wheel of a vehicle. Tires and wheels are designed so that when the tire is inflated, the tire pressure pushes the bead of the tire against the inside of the wheel rim so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
A run-flat tire is a pneumatic vehicle tire designed to resist the effects of deflation when punctured, allowing the vehicle to continue to be driven at reduced speeds for limited distances. First developed by tire manufacturer Michelin in the 1930s, run-flat tires were introduced to the public market in the 1980s. They have increased in popularity over time.
A tire-pressure monitoring system (TPMS) monitors the air pressure inside the pneumatic tires on vehicles. A TPMS reports real-time tire-pressure information to the driver, using either a gauge, a pictogram display, or a simple low-pressure warning light. TPMS can be divided into two different types – direct (dTPMS) and indirect (iTPMS).
A tubeless tire is a pneumatic tire that does not require a separate inner tube.
A spare tire is an additional tire carried in a motor vehicle as a replacement for one that goes flat, has a blowout, or has another emergency. Spare tire is generally a misnomer, as almost all vehicles actually carry an entire wheel with a tire mounted on it as a spare rather than just a tire, as fitting a tire to a wheel would require a motorist to carry additional, specialized equipment. However, some spare tires are not meant to be driven long distances. Space-savers have a maximum speed of around 50 mph (80 km/h).
Inspection and maintenance of tires is about inspecting for wear and damage on tires so that adjustments or measures can be made to take better care of the tires so that they last longer, or to detect or predict if repairs or replacement of the tires becomes necessary. Tire maintenance for motor vehicles is based on several factors. The chief reason for tire replacement is friction from moving contact with road surfaces, causing the tread on the outer perimeter of tires to eventually wear away. When the tread depth becomes too shallow, like for example below 3.2 mm, the tire is worn out and should be replaced. The same rims can usually be used throughout the lifetime of the car. Other problems encountered in tire maintenance include:
The Dunlop valve, is a type of pneumatic valve stem in use—mostly on inner tubes of bicycles—in many countries, including Japan, Korea, India, Pakistan, Sri Lanka, most European countries, and a number of developing countries. The Dunlop valve has a wider base than a Presta valve, similar enough in size to a Schrader valve to use identically drilled valve holes in rims, but it can be inflated with a Presta valve adapter. The inner mechanism of the valve can be replaced easily, without the need for special tools.
Canned tire inflators are single-use devices intended to provide a quick, temporary solution to drivers who experience flat tires. These devices seal the punctured tire and then reinflate it with pressurized gas, providing enough pressure to allow the auto to be driven for a short period at low speed. This allows the motorist to have the damaged tire professionally repaired or replaced, avoiding the need to replace the wheel at the roadside.
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 the lateral forces necessary for balancing and turning, and generate the longitudinal forces necessary for propulsion and braking. Although the use of a pneumatic tire greatly reduces rolling resistance compared to the use of a rigid wheel or solid tire, the tires are still typically the second largest source, after wind resistance, 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 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 onto a specially designed rim, referred to as a "sprint rim" in Britain, and just a "tubular rim" in the US, of a bicycle wheel.
A motorcycle tyre is the outer part of motorcycle wheel, attached to the rim, providing traction, resisting wear, absorbing surface irregularities, and allowing the motorcycle to turn via countersteering. The two tyres' contact patches are the motorcycle's connection to the ground, and so are fundamental to the motorcycle's suspension behaviour, and critically affect safety, braking, fuel economy, noise, and rider comfort.
Louis Désiré Auguste Rustin (1880-1954) was a French cyclist and repairer of tyres in Paris who invented the puncture patch. Car and bicycle tyres had until then been complicated to mend after the inner tube, which held the air, had been penetrated through the outer tyre by a flint or other sharp object. Rustine's solution was a small disc of thin rubber to stick to the inner tube over the hole. He patented his invention in 1921 and presented it at a meeting of the Touring Club de France in 1922. Puncture patches are still commonly known in France as rustines.
The following outline is provided as an overview of and topical guide to tires:
An inner tube is an inflatable torus 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 outer tire provides grip and protects the more fragile tube.
References
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