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A run-flat tire is a pneumatics 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.
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.
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 Rubber launched the Total Mobility Tyre (later Denovo) "fail-safe" wheel and tire system that became optional equipment on the Rover P6 3500 in 1973, 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)Pressure Zero Tire: American Engineering Group wins award for its zero pressure tire http://www.tractionnews.com/american-engineering-group-wins-award-zero-pressure-tire-technology/ 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 Polaris RZR, 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 at around . 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. 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.
There are also a number of tire 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.
The usual standard of performance, especially for military or security vehicles, are the Finabel standards.
Former US President Barack Obama's presidential limo, "the Beast", had Goodyear Kevlar lined run-flat tires.
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