UNSUNG HEROES
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• No matter what power, what weight, what cab comfort, what suspension or what driveline a manufacturer may put into his truck, bus or coach, the ultimate performance determinant of that vehicle is going to be a round, black, flexible object whose behaviour under stress is variable and perhaps unpredictable.
Furthermore, no matter how good that round object may be, its own chances of doing anything to translate the vehicle designer's ideas into motion are limited. It is expected to face unpredictable and harsh road conditions and surfaces, extremes of temperature, abuse — and all the while do its job via a contact area little greater than the size of your hand.
For all that, tyre users have never accepted that there must be limitations in tyre performance, neither have tyre manufacturers lain down and accepted that no further improvement can be made. The commercial vehicle tyre of today is a far more sophisticated object than that of twenty years ago: it is made better, performs better, and lasts better.
There are still problems, however. Some tyres — such as those on tri-axle trailers — can suffer from almost unacceptable levels of stress from scrubbing round tight corners when fully-laden. Modern high-performance, lowprofile radials are more sensitive to mistreatment and misbalance than were their high-section, low-performance crossply predecessors. The tyre manufacturers have the problem of having created a much better, longer-lasting, more expensive product for which there is, by definition, less of a demand than there was for the old low-life tyres.
The best efforts of the tyre designers have created tyres which sweep more surface water from the roadway, and thereby have much better grip. The price to be paid is much more spray — which is why we have included spray-suppression equipment in this supplement. The tyres with better grip have often proved to have a greater rolling resistance, so that improved grip has to be traded for poorer fuel consumption. Likewise, the more grippy tread patterns tend to create more noise in an era when the reduction of drive-by noise is becoming a vital concern to vehicle builder and user alike.
Tyres and wheels tend not to feature in the headlines, but they form a vital part of the technology of the modern motor vehicle and of its operating costs. In this supplement we have gathered together some of the most important aspects of modern wheels and tyres, and listed most of the tyres which are available for heavy commercial vehicles in Britain. We have also listed the expensive range from one of the country's many remanufacturers, to show just how widespread is the choice facing the commercial vehicle operator today.