Your car has a flat tire, and the modern compact spares are pretty easy to handle and in fifteen minutes you can install the spare and be back on the highway. But, it you are not careful, you can lose your spare before reaching the next exit.
A functional spare is a comforting accessory, but it must be kept properly inflated or checked periodically that the rubber is in good condition. Also, a spare that is buried under tons of trunk trash is useless.
Under-inflation: If your spare is low, it may shred before you reach home or the tire shop. This is the most common cause of spare tire failure. Check the pressure of the spare, as well as the other four tires every month or two.
Dry Rotting: Tires, like clothing, tend to deteriorate with age. Tires have a shelf life, and you should watch for small cracks in the sidewall, which indicates you should replace your spare tire.
Inaccessibility: The main reason spare tires have the above problems is their inaccessibility. If you do your own vehicle maintenance, you should periodically clear out the trunk to check the spare's condition. If you take your car to a shop, most automotive technicians will check your spare if they can get to it, but few will move your cargo to do it.
While some space-saving spares are made to travel up to 3,000 miles at highway speeds; most are limited to 50 m.p.h. Reserve them for temporary use and replace it with the proper full-size tire at your FIRST opportunity. This way your spare can return to being a spare, and you won't have to replace two tires. The compact spare and wheel are designed for your vehicle only, and should not be used on another car.