Run flat tires are car tires which are designed so that they can be used when punctured or extremely low on air. The basic genesis of the run flat design actually dates to the late 1800s, but it didn't become more widely available until the 1970s, and it is primarily a feature offered on luxury cars, especially sports cars. There are a number of advantages to using run flat tires, but there are also some distinct disadvantages which should be considered before equipping a car with run flat tires.
Several different systems can be used for run flat tires. Self sealing tires have an inner lining which automatically seals puncture holes, thereby keeping the tire inflated if it is punctured. Self supporting tires have rigid sidewalls which allow the tire to be used even if it has been punctured or partially deflated, and auxiliary supported systems have a secondary support ring.
Run flat tires are also equipped with sensors which provide data about tire pressure to the data, along with warnings. The car will usually need to be driven at reduced speed if the tires have been compromised, and it has a relatively short range. It is still possible to have a blowout if the tire is damaged in a way which causes catastrophic failure or if the car is driven despite run flat warnings indicating that the tire needs to be changed or repaired.
The big advantage to run flat tires is safety. Blowouts and tire deflation can be serious safety risks for drivers. As with other measures which increase vehicle safety, using run flat tires can decrease insurance premiums, as insurance companies want to provide an incentive for customers to increase safety. These tires are also convenient, as it isn't necessary to stop right away to address a flat. For people who do a lot of driving, especially at high speeds such as those found on the freeway, run flat tires can be extremely useful, and they may even save lives.
However, run flat tires can be substantially more expensive than conventional tires, and there is some dispute about the tread wear over the life of the tires. These tires are also stiffer, making for a stiffer ride and less fuel efficiency, which can be an issue for some drivers. Additionally, many cars designed for use with run flat tires lack an area for a spare tire, which means that if a driver opts to switch to conventional tires, there's no room for a backup in the event of a flat.