If you have a flat tire, park your car on a level, hard surface away from traffic if possible. Turn on the hazard warning lights, install an emergency stop sign or flashing light in accordance with the Road Traffic Regulations. Ask passengers to leave the car and move to a safe place.
Apply the parking brake, engage 1st or reverse gear. If the transmission is automatic, set the control lever to the "P" position.
(This publication was borrowed from an online resource: «BMWman»)