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Run-flat tires

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Run-flat tires

For more than 50 years, Jacques Bajer has championed the cause of tire structural integrity in one way or another. His work with Ford Motor Co., beginning in 1955, led to the creation of a tire uniformity grading machine. In 1964, he almost single-handedly developed low-profile tires for the 1964 Lincoln and Thunderbird. They performed so well that Ford made them standard equipment on all its vehicles the following year.

The French-born engineer also owns a patent for a "casing preparation method" used in producing quality retreaded tires.

He is perhaps best known, however, for radializing the domestic automotive industry. Bajer didn't invent the radial tire, but when he convinced Ford to offer them as options on its vehicles, the radial tire era began.

Bajer opened his own consulting company, Tire Systems Engineering Inc., in 1970. More than 30 years later, he is still teaching automotive industry neophytes about how everyone, especially the consumer, is better served if the tire is analyzed not in a vacuum but in conjunction with the vehicle and the road. And that, perhaps, will be his legacy: as a teacher.

Knowing what your tire inflation pressures are is not absolute, unless tied to other equally important aspects of tire operation. They include ambient temperatures and variations thereof; tire deflections and internal cross-sectional structure component temperatures; the state of tire structural integrity and tread wear; tire age; tire service history; the effects of punctures; external and internal bruises; the quality of tire repairs; etc.

All the aspects are too complex for consumers to really be concerned with. Consumers trust that tire and vehicle producers conduct all the tire validation tests required to protect their interests and safety prior to releasing tires for public usage.

Recently, and as a result of extensive media coverage of catastrophic tire failures -- whatever the root cause -- consumers have become more conscious of the safety aspect of tires. But are they looking after their tires more today than in the past? I doubt it.

So, from such a vantage point, one could conclude that, if early on a warning of an impending catastrophic tire failure, although statistically rare, could be provided to the vehicle driver, progress would be achieved. Certainly with today's available sensing and computation technologies this is entirely possible and would protect consumers from the potentially tragic consequences of their ignorance and negligence of tire maintenance.

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Such a warning system also would protect consumers against the effects of possible tire manufacturing variations not detected during the tire manufacturing process. Also, the system could automatically slow down the vehicle speed to 20 mph or less as soon as a serious tire structural integrity degradation that could lead to a catastrophic tire failure and/or vehicle accident has been detected and communicated to the vehicle's driver.

All this sounds complicated, but anti-lock brakes, stability and traction control systems onboard many vehicles today also are complicated (and expensive) and, statistically, also rarely come into action under real world consumer vehicle service operating conditions. So what is the consumer really getting?

Run-flat tires

Run-flat tires or tire/wheel systems are not used extensively today, although usage may grow. In the meantime, they are promoted on the basis that they provide consumers with peace of mind and vehicle mobility when tires operate severely or fully deflated.

However, run-flat tires also are prone to structural integrity degradations and consequences thereof. Sometimes even the wheel and the tire internal supporting platform can structurally fail, depending upon what the vehicle encounters, including bad road surface conditions. These failures are not always related to consumer negligence in maintaining proper tire inflation pressure, but historically it always has been convenient to blame consumers when something goes wrong with tire operation.

Actually, consumers believe that tires are infallible and can perform reliably, even with little or no maintenance. In fact, statistically they do, for tires are one of the few vehicle components capable of withstanding severe punishment extremely well.

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Run-flat tires of the self-supporting type, or of the internal supporting platform type, are very expensive to consumers at replacement time, because they use more raw materials and components, which, in turn, require more manufacturing equipment and tooling, including new molds, and more time and energy to produce them. They not only can wear out their treads more rapidly and unevenly as compared to standard tires, but also can consume more energy in the process of providing vehicle functions.

Some run-flat tires of the internal supporting platform type use a larger, heavier and different wheel architecture than a standard wheel. The internal supporting platform also adds weight to the rotating wheel mass, which, in turn, requires more power to propel and more power to stop the vehicle, hence resulting in a less efficient rotating system as compared to a standard, reasonably sized tire/wheel assembly of 15- or 16-inch wheel diameter or less.

Run-flat systems can pose service logistic problems and can be less service- and user-friendly than standard tires of a normal aspect ratio, say, 65 series. All this can create an economic "Catch-22" situation detrimental to consumers.

The hard questions are these:

1. Has it been clearly proven that run-flat tires are beneficial to consumers?

2. Would consumers really be safer using them?

3. Are vehicle and tire producers validating run-flat tires under vehicle operating conditions fully representing the experience consumers encounter throughout the world?

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What consumers already know is that today's standard tires are economical and reliable, even when operating under the most adverse conditions. They also are relatively more user- and service-friendly as compared with, so far, run-flat tires or run-flat tire/wheel systems of any type.

Realistically, all the consumer needs is the following:

1. a well-designed, developed, produced and applied, structurally more robust, longer-wearing standard type tire of adequate size and load reserve;

2. a well-developed tire operating condition monitoring system such as mentioned earlier;

3. a vehicle that is equipped with a full-size spare tire/wheel assembly with significantly improved tools to handle it in an intuitive manner; and

4. the means to inflate tires from onboard the vehicle when such need arises.

That's all.

Solution to the basic problem

Satisfying the public's need first, and assuming that the pneumatic tire will continue to prevail in spite of its drawbacks, it is my opinion that, from all the field experience acquired with radial ply tires over the last 57 years, the solution lies in producing structurally much stronger and lighter tires, featuring much longer mileage (routinely 100,000 miles) and significantly improved operating smoothness and puncture resistance. Such tires would not only better serve the public's need, but also be the most effective way the tire industry could contribute to a much-needed raw material and energy conservation effort.

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Will the pneumatic tire be perpetually used? As my late friend, Tom French, former manager of tire design and development at Dunlop England, with whom I worked for many years, states in his 1988 book Tyre Technology, "the reinforced rubber pneumatic tyre will essentially remain an engineering component which is awkward to produce, but which has a guaranteed future, because of its unique and irreplaceable contribution to most forms of wheeled transport."

Recently, the development of a relatively light tire/rim system not requiring pressurization was announced. Such system, if commercially successful, would eliminate the major problem of the pneumatic tire since its invention by Robert William Thomson 160 years ago: punctures and subsequent deflations.

Many over the years have attempted to solve this basic problem; they all failed. So, let's wait and see.

In the meantime, implementing the solutions outlined earlier can almost immediately benefit the public. That leaves us with this question: Is the current tire business environment, essentially dominated by marketing and sales, and with its emphasis on the next quarterly profit report, conducive to such development?

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