The run-flat tire is really a sign of our times. The idea and intentions of this invention are easy for the average person on the street to understand. Using an extemely stiff sidewall, the run-flat tire can be driven safely for about 50 miles or so at 50mph without air. On top of that, they allow for roomier trunks, as most vehicles equiped with run-flat tires do not have spare tires of any size. Since the tires can be driven on without air pressure, a person can drive home/out of danger on them instead of having to change the tire on the side of the road or call roadside assistance. Run-flat tires are so stiff that they require tire pressure sensors, as some drivers may not be aware that they have a "flat" tire.
Automobile companies like run-flats for a variety of reasons. In addition to avoiding the cost and space of a spare/doughnut tire in the trunk, the run-flats usually require special equipment for installation that dealers and only large automotive tire shops have, thus giving them(the automotive dealers)more after-sale business.
There are two reasons why a person usually gets a flat tire and in both cases the run-flat makes a bad situation worse. The first situation and most common is when a tire runs over something sharp like a nail. On a regular tire, the consumer usually has the option to change out the temporarily defective tire for a spare and fix it at their leisure. On a run-flat, once the tire has been driven without air, it is considered junk. The consumer must then buy a new tire, usually to the tune of over 200 dollars, after the tire is punctured . The second scienario, which is far less common, is when the tire is shredded and cannot be repaired. In this stituation, a spare tire can be mounted on a non-run-flat equiped vehicle and the owner can then head to the local tire store and purchase a tire. The run-flat tire owner in this situation is now stuck and cannot move their car until help via tow truck arrives. In addition, they now have to find a shop/dealer that has their tire and the equipment to mount it.
The consumer is the real loser here in the long run. Many are sold cars with run-flats and only to find out later that they have over a thousand dollars worth of tires on their vehicles that must be replaced every 20-40 thousand miles.
