Run-flat tires are a type of 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. They have specific technology that allows you to drive for a limited distance at a reduced speed after a puncture or a drop of tire pressure. The benefits of run-flat tires include 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. They are more stable than conventional tires in a puncture situation and can help maintain steering control over the vehicle during this process. Run-flat tires have two primary types of systems: the self-supporting system and the support ring system. The speed and range of run-flat tires are limited, and they cannot be driven over 50 miles per hour most of the time, and usually offer only up to 50 miles of extended mobility. The cost of run-flat tires can be more than double other tires of comparable size, and they cannot be run flat if the flat is due to sidewall damage, a common cause of flats. Only vehicles that originally were equipped with run-flat tires should mount them, and it is not recommended to mix different run-flat technologies/products together.