Flat tire changes in Dallas.

A driver comes out, jacks the car up safely, takes the flat off and puts your spare on. It is a simple job on a quiet street and a far less simple one on a highway shoulder with traffic passing a few feet away, which is the main reason to have someone else do it.

A tire change depends on the car having a usable spare. Many newer cars come with an inflation kit instead, and spares that have sat in the trunk for years are often flat themselves. If you can, check before you call. If there is no spare, or it will not hold air, the answer is a tow to a tire shop instead.

If the wheels have locking lug nuts, there is a special key for them, usually in the glove box, the center console, or with the jack and tools under the trunk floor. Without it the wheel cannot come off. Finding it before the driver arrives saves the most time of anything you can do.

Most spares are compact temporary tires, the narrow ones, and they are not meant for highway speeds or long distances. Check the sidewall for the speed limit printed on it and drive to a tire shop rather than carrying on with your day. If the flat was caused by damage to the wheel itself — a bent rim from a pothole or a curb — mention it, because a spare does not fix a wheel that will not seat properly, and that is a tow rather than a tire change.