Runflat

Run-flat tires are designed to allow a vehicle to continue being driven after a loss of air pressure, enabling the driver to reach a safe location without immediately changing the tire. They typically support the weight of the vehicle for a limited distance and at a reduced speed, with exact limits determined by the tire’s design and the vehicle manufacturer’s recommendations. Most run-flat tires rely on a reinforced structure to resist collapse when punctured, so the tire can remain drivable even when flat.

There are two main categories of run-flat tires. Self-supporting run-flat tires use strengthened sidewalls to bear the load when air pressure is lost. Other systems use an external support mechanism, such as a rigid ring or a separate reinforcing component, to carry the vehicle’s weight after inflation loss. Some modern designs combine run-flat features with tire pressure monitoring systems to alert the driver to a puncture.

Repair and replacement practices vary. In many cases, punctures in the tread area of run-flat tires can be repaired, but damage to the sidewall or prolonged driving while flat may require tire replacement. Many manufacturers and service providers caution that run-flat tires are not always repairable after certain types of damage. Additionally, vehicles equipped with run-flats often omit a spare tire, relying instead on the run-flat capability or a sealant kit.

Trade-offs include a typically firmer ride, higher tire cost, and sometimes shorter tread life. Run-flat tires are most common on vehicles designed to accommodate them, and drivers should follow the vehicle maker’s guidance regarding speed, distance, and replacement.