It wasn't all that long ago that the motorist unfortunate enough to end up with a nail in a tube-type bias-ply tire replaced it with his spare. After a few choice words and a kick of annoyance at the flat tire, he drove to the nearest service station to have the flat repaired. And that was that.
But times have changed. Today, cars are faster. Tires give far better performance and now are so reliable users hardly give them a second thought.
What hasn't changed are the nails and screws on the highway that still find their way into tires.
The hiss of escaping air from a punctured tire is heard less these days. Modern, tubeless, steel-belted radials can absorb nails and often continue running because air loss-and the resultant drop in inflation pressure-occurs gradually. With this in mind, the question arises: ``Is the spare tire really necessary?''
Of all the parts that could conceivably immobilize an automobile, the tire is the only one for which the automaker provides a replacement to be carried in the vehicle.
When the tubeless tire came on the market in the mid-1950s many thought that would be the end of the spare tire. But motorists still insisted on having a spare tire. Thus the spare is still with us-although in a changed form.
Research shows that many of our country's 170 million licensed drivers pay little heed to their tires, and to no one's surprise, the most neglected of all is the spare tire. Most owners have little idea of the type of spare carried in their cars because they are so rarely used.
Despite the fact that the average driver will need a spare tire only once in seven years, few motorists will buy a new car without this underused spare part.
In fact, four out of five new-car buyers surveyed said they would pay a higher price rather than forego their spare tire.
Obviously, such an attitude is more emotional than rational, as it does not really correspond to the risk of breakdown on the road. Motorists who consider the spare their most important piece of emergency equipment underestimate the risks of other types of mechanical failure that occur with greater frequency.
Also, it has long been the goal of automakers to abolish the spare due to all the inconvenience it causes in terms of finding a place to store it, the extra weight it adds to the vehicle and the effect of this on fuel consumption.
So far, the most popular alternative to the full-size spare among automakers is the smaller and narrower mini-spare, which enables the motorist to get himself going and it saves the manufacturer a great deal of money.
It has been an important step forward in offering the car manufacturer the most in terms of space, weight and cost savings. As a result, mini-spares, together with smaller tire wells, have become standard equipment on many new cars.
Major drawbacks to the mini-spare are its limited life expectancy (3,000 miles), speed limits for its use (45 mph) and its higher in-flation pressure, which results in air leakage after long periods of storage in the trunk. And for a motorist with a flat tire, few experiences are more unsettling than finding out your spare also is flat.
Motorists also must figure out where to put the full-size punctured tire if the car has a small tire well and the trunk is full of luggage.
Tire dealers and retreaders have benefited somewhat in past years by being able to supply new or retreaded tires as spares to replace original equipment mini-spares, when the tire storage areas were large enough to accept a full-size tire.
However, these opportunities have been declining as more new cars have small tire wells.
An important factor which seems to have been overlooked is that although a 13-pound lighter tire assembly may save fuel, there is no ecological advantage in the long run. Most mini-spares will be scrapped without ever being used, thus the materials used to manufacture them will be wasted.
Today's cars are equipped with computers that operate the engine, transmission, speedometer, cruise control and anti-lock brakes-all of which depend on a standardized number of tire revolutions.
Thus any variations in rolling radius that translates into a change in revolutions per mile can confuse these computers.
The longer life of the radial tire, together with improved highway construction, already have combined to limit tire consumption and retreading.
For the future existence of the tire dealer and retreader, an increasing percentage of total sales must come from tire and vehicle servicing and less from tire sales.
The way things seem to be going, it's only a matter of time before we see the demise of the spare tire as automakers modify new car designs.
When that time comes, passenger tire dealers and retreaders will face yet another challenge that only can be overcome by improving product quality, productivity and by receiving adequate compensation for the additional services they're asked to provide.