Flat tire

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, letting air escape. Depending on the size of the puncture, the tire may deflate slowly or rapidly.

Some tires, particularly those with a slow leak, can be repaired and re-inflated; others, especially those with worn tread, must be replaced.

Where a flat tire occurs, drivers are advised to slow gradually and pull off the road. 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 an accident.

On a bicycle, a flat tire will compromise handling, as well as increasing rolling resistance.

A UK source reports that flat tires account for about 10% of motor vehicle breakdowns.

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 which can easily be removed by a tire repair professional before a permanent repair is made. Canned tyre 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 water-based sealant can be injected into the tire also through the valve stem. This contains less harmful chemical and no aerosol gas. The sealant can then be driven into the tire using an air compressor.

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Wikipedia