Replacing a flat tire is one of the few automotive chores that hasn't changed much in decades. But improvements in tires mean that many of us have had little or no experience doing it. If one of your car's tires goes flat while you're driving, stay calm. The car may seem unsteady or pull to one side, but don't jam on the brakes. Use the turn signal and steer out of traffic. Use steady, easy pressure on the brakes. If you stop at the side of the road, use the emergency flashers. The car should be on a solid, level surface. You can drive a short distance, very slowly, if necessary to reach a safe spot. Put the transmission in park (or, with a manual transmission, reverse). Set the parking brake. Locate the spare tire and jack. Your vehicle's owner's manual includes instructions for using the jack, and many cars duplicate the instructions on a decal near the spare.