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.[ citation needed ]
There are three basic technologies currently available, described below.
The origins of the commercial self-supporting run-flat tire started in 1935 with a tire that had a fabric inner tire. The tire was advertised as a protection against blowouts, a common and dangerous occurrence in the 1930s. [1]
In 1934, Michelin introduced a tire that was based on technology developed for local commuter trains and trolleys. It had a safety rim inside the tire which if punctured would run on a special foam lining. The tire was sold for military use and for specialized vehicles like bank armoured cars. It was advertised as "semi-bulletproof". While the tire performed as advertised it was far too expensive to be a feasible option for most private automobile users. [2]
In 1958, Chrysler teamed with Goodyear Tire and Rubber Company to offer Captive Air run-flat tires using an interlining to carry the weight.
In 1972 Dunlop launched the Total Mobility Tyre (later Denovo) "fail-safe" wheel and tire system that became optional equipment on the Rover P6 3500 in 1973, [3] and by 1983 evolved into the TD/Denloc which became standard equipment across the whole Austin Metro range.
Most recently, Bridgestone and Pirelli run-flat tires are supplied on some new model BMW cars. The automaker promoted these as a safety feature and as an alternative to carrying a spare tire.
Pressure Zero Tire (PZT) [4] was pioneered by American Engineering Group (AEG) for US Special Forces. AEG prototype dissipates heat and has the tire flexibility and strength to support the heavy military pick-up weight while providing a relatively smooth ride. The durability characteristics of this design were studied further on four different tire sizes for ATV Polaris, Toyota Hilux, and Toyota Land Cruiser & GMV 1.1. special operations vehicles.
Self-supporting run-flat tires are now common on light trucks and passenger cars and typically allows the vehicle to be driven for 50 miles (80 km) at around 50 miles per hour (80 km/h). However, if the tires are subject to this kind of misuse, wheels may become damaged in the process, and repair may be impossible or unsafe, especially if the tire is punctured in the sidewall or at the edge of the tread. These tires carry a 20% to 40% weight penalty over similar standard tires and the thicker sidewall also means higher rolling resistance, which reduces the vehicle's fuel economy. [5] However, the weight penalty of the individual tire is usually more than compensated by the fact that the vehicle need no longer carry a spare, as well as the equipment needed to swap in the spare. The thicker sidewall however results in more road imperfections filtering through the tire to the rim and hence to the car, which results in a harsher ride. [6]
These tires contain an extra lining within the tire that self-seals in the event of a small hole due to a nail or screw. In this way, the loss of air is prevented from the outset such that the tire is either permanently self-repairing or at least loses air very slowly.
There are also a number of retrofitted tire sealants which act in a similar way to self-sealing tires. These compounds are normally injected through the tire valve. The rotating force then distributes the compound onto the inner surface of the tire to act as a self-sealing lining within the tire.
In this system, there is an additional support ring or insert attached to the wheel that can support the weight of the vehicle in the event of a loss of pressure. The run-flat insert has an unsurpassed ability to carry heavy vehicle loads for long distances at high speeds. It is therefore the normal run-flat selection for military vehicles, high-level executive protection vehicles, and armored vehicles [7] used by government, aid groups, or private contractors in conflict zones.
The basic benefit of using run-flat tires is continued mobility in case of a loss of air pressure, due either to a "normal" puncture or to a hostile deliberate act including a bullet strike while the vehicle is traveling at high speed. Performance criteria are therefore in terms of distance and speed at which the vehicle can escape without becoming immobile and the steering control over the vehicle during this process.
The usual standard of performance, especially for military or security vehicles, are the Finabel standards. [7]
Run-flat tires accounted for less than 1% of replacement tire sales in the U.S. in 2005. In 2006, it was expected that such tires would gain popularity with armored vehicle manufacturers, but growth figures were slow with one major model, the Michelin PAX System, no longer being developed by the manufacturer (though replacements will be produced for the foreseeable future). [8] A Michelin study released in 2008 found that 3% of drivers worldwide want run-flat tires. U.S. market share is well below 1%. American Honda Motor Co. announced that the 2009 Honda Odyssey Touring and Acura RL were its last models available with run-flat tires and with Honda no longer using run-flats. This leaves only a handful of volume manufacturers offering them as standard fittings and only on some models. An exception is BMW, who are the largest fitter of run-flats as original equipment. [5]
Former US President Barack Obama's presidential limo, "the Beast", had Goodyear Kevlar lined run-flat tires. [9]
The cost can be more than double other tires of comparable size. Also, run-flat tires cannot be run flat if the flat is due to sidewall damage, a common cause of flats. Generally, under ideal circumstances, the speed and range of run-flat tires is limited. Run-flat tires cannot be driven over 50 miles per hour most of the time, and usually offer only up to 50 miles of extended mobility. These limitations lower the value of the extra expense for many buyers. In certain applications, depending on the vehicle, specific tire design, and driving surface, a run-flat tire can provide from 25 miles to 200 miles driving while flat with limited speed.
For Goodyear Tire, one effect on market share is the policy to prohibit the repair of tires punctured by nails or other road hazards; while Goodyear tires can be repaired, the manufacturer's warranty and liability is voided.[ citation needed ]
A tire 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.
Michelin, in full Compagnie Générale des Établissements Michelin SCA, 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 larger than both Goodyear and Continental. In addition to the Michelin brand, it also owns the Kléber tyres company, Uniroyal-Goodrich Tire Company, SASCAR, Bookatable and Camso brands. Michelin is also notable for its Red and Green travel guides, its roadmaps, the Michelin stars that the Red Guide awards to restaurants for their cooking, and for its company mascot Bibendum, colloquially known as the Michelin Man, who is a humanoid consisting of tyres.
The Acura RL is a full size luxury car that was manufactured by the Acura division of Honda for the 1996–2012 model years over two generations. The RL was the flagship of the marque, having succeeded the Acura Legend, and was replaced in 2013 by the Acura RLX. All models of the Legend, RL and RLX lines have been adapted from the Japanese domestic market Honda Legend. The model name "RL" is an abbreviation for "Refined Luxury."
Tire rotation is the practice of moving the wheels and tires of an automobile from one position to another, to ensure even tire wear. Even tire wear extends the useful life of a set of tires, but the value of this is disputed.
The Tweel is an airless tire design developed by the French tire company Michelin. Its significant advantage over pneumatic tires is that the Tweel does not use a bladder full of compressed air, and therefore cannot burst, leak pressure, or become flat. Instead, the Tweel's hub is connected to the rim via flexible polyurethane spokes which fulfil the shock-absorbing role provided by the compressed air in a traditional tire.
A radial tire is a particular design of vehicular tire. In this design, the cord plies are arranged at 90 degrees to the direction of travel, or radially. Radial tire construction climbed to 100% market share in North America following Consumer Reports finding the superiority of the radial design in 1968, and were standard by 1976.
A self-sealing fuel tank (SSFT) is a type of fuel tank, typically used in aircraft fuel tanks or fuel bladders, that prevents them from leaking fuel and igniting after being damaged.
Low rolling resistance tires are designed to reduce the energy loss as a tire rolls, decreasing the required rolling effort — and in the case of automotive applications, improving vehicle fuel efficiency as approximately 5–15% of the fuel consumed by a typical gas car may be used to overcome rolling resistance.
Automotive tires are described by several alphanumeric tire codes or tyre codes, which are generally molded into the sidewall of the tire. These codes specify the dimensions of the tire and its key limitations, such as load-bearing ability and maximum speed. Sometimes the inner sidewall contains information not included on the outer sidewall, and vice versa.
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 flat tire 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 the puncturing of the tire by a sharp object, such as a nail or pin, letting the air escape. Depending on the size of the blowout, the tire may deflate slowly or rapidly.
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 ride-on lawn mowers and motorized golf carts. They also are used on heavy equipment required to operate on sites where risk of tire punctures is high. Tires composed of closed-cell polyurethane foam are also made for bicycles and wheelchairs.
Tire uniformity refers to the dynamic mechanical properties of pneumatic tires as strictly defined by a set of measurement standards and test conditions accepted by global tire and car makers.
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:
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.
Tire mousse is a component in certain types of off-road run-flat tires, designed to allow them to maintain functionality despite a puncture. It is a ring of flexible foam that is placed inside a tire before it is fitted on the rim. The original run-flat mousse, called Bib-Mousse, was developed in 1984 by Michelin, for use on motorbikes in enduro, rally-raid and motocross events. In 1987, Michelin debuted its ATS system on the works Renault 11s of Jean Ragnotti and François Chatriot on the Acropolis Rally. It won the Technological Innovation Award in 1988.
The Michelin PAX is an automobile run-flat tire system that utilizes a special type of rim and tire to allow temporary use of a wheel if its tire is punctured. The core of Michelin's PAX system is the semi-rigid ring installed onto the rim using special equipment. It provides support to the tire and its sidewall to allow emergency operation at limited speed until such time as the tire can be replaced. Cars that use the system include supercars like the Bugatti Veyron EB 16.4, luxury cars like the Rolls-Royce Phantom, and more common vehicles like the Honda Odyssey and Nissan Quest.
Stemco is a Longview, Texas, based company that manufactures and distributes products for the global commercial vehicle market. Its major product categories include wheel end products, brake products, intelligent transportation systems and suspension components.