As a result, the tire is able to support the weight of the vehicle and passengers for a limited time after the loss of air pressure. In case of a puncture or cut, the tire can be driven on for 50 miles up to the speed of 50 mph, which prevents the driver from being stranded on the side of the road. Run flat models cannot be mixed with regular tires, as their constructions are heavier, and they are usually made for vehicles without space for a spare tire.