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Radial Tyre Evolution – A technology revolution with parallels

Published on 1st November 2010

If one were to broadly classify the evolution of technology in the tyre industry, of course with the exception of the Stone Age version often seen in cartoons with a club wielding cave man, they could broadly be classified into three categories – bias, radial tyres and tubeless radial tyres.

Radial tyre that is commonly used in passenger cars and increasingly in commercial vehicles have reached the present zenith in a way quite unique to itself – and is worth a brief look into, to understand how some technologies have had to take the tough ride before gaining general public acceptance. In its initial days in the US, radial tyre technology was very nearly dumped by the then pundits of the automobile industry as a virtual non starter and a gimmick holding no promise, not destined to make any progress worth investing time and money in.

The early sixties saw the US tyre industry embroiled in a controversy over an improvement based on an otherwise technically sound engineering improvement – to reduce the conventional 4 ply structure to a 2 ply structure – in effect reducing the side wall thickness. In the earlier bias ply tyre, the fibers (rayon initially and then substituted with nylon and subsequently polyester) were strung from one bead to the other bead across the periphery of the tyre, with both the start and finish at the same angle. This arrangement was easy to manufacture and served the purpose of softening the rough ride of cars.

But they were not easy on the steering wheel and when they did turn, they tended to turn all at once. These tyres couldn’t be left standing for long at one position and they stretched with age. They were not good at retaining air pressure and were prone to ‘squirm’ – the result of the tyre’s original shape resisting the flat surface of the road. These tyres could hardly cross the 25,000 km mark due to the heat that tyres generated at high speed – tyre change every year was an expense that owners had come to accept.

The concept of radial tyres was introduced in 1914, though it never took off as a viable product until much later. The two Englishmen who patented their development – Gray and Sloper crossed cables radially in a marked deviation to convention in their effort to stiffen the sidewalls. Bonding rubber to steel was a technique yet to be developed and their idea stalled for want of process expertise.

Michelin, however kept the idea alive, developing their own rubber encapsulated steel cords placed radially on the tyre, achieving lesser rolling resistance and operating temperatures. Michelin got a patent for their variant of radial tyres, after running an extra steel belt lengthwise along its circumference giving their tyres directional ease and stability. More importantly, it more than doubled the life of the treads in comparison. The radial cords made the side walls more flexible making the ride more comfortable and was not acting against the surface of the road as the conventional tyres. The rigid steel belts along the treads improved the mileage and performance of the tyre. European automakers were quick to take up on this significant development.

American tyre manufacturers kept a wary eye out for this development, but busied themselves with improving the bias tyre’s design to respond to the market requirement of low profile tyres – about two thirds height to width ratio – enhancing traction, bigger wheels and presented a road hugging design. It also threw up the possibility to reduce weight and friction. A thinner side wall was a logical step towards this. But what the industry did not foresee was a spate of quality issues serious enough to catch the attention of the Senate.

It was at this point in time that some pioneers with prior exposure to radial tyres, introduced the radial tyres to American cars. They were subject to a lot of flak, but their belief and perseverance born out of their personal conviction on the future of this technology finally bore fruit. But the car designers found that the cars had to be re-designed to adapt to the radial tyres, since the seeming ‘harsh driving’ experienced when using radial tyres was because the precise handling afforded by radial tyres were throwing up the inherent weakness of the American auto engineering. What was required was to undo the adaptations made earlier to suit the bias ply tyres. The tight steering required by bias tyres was done away with since radial needed much lesser steering input. The vibrations of the rear tyre had to be isolated and bushings were added to cushion the jolts taken by radial tyres on rough patches.

Even as late as in 1970, the trade watchers had written off the possibility of radial tyres outdoing belted bias tyres. What had swung the history in favor of radials was an agreement between Ford and Michelin in 1968 to release Ford’s Lincoln Continental Mark III with radial tyres as standard, following an aggressive pricing strategy by Michelin. What followed was a desperate scram by other manufacturers to adapt to the new technology, over which Michelin had established firm but fiercely guarded expertise. Tales abound about several acts of industrial espionage to acquire this much coveted process knowledge and the efforts by Michelin to counter all such moves.

In 1973, 11 percent of GM cars and 26 percent of Fords were being equipped with radials Two years later, it was 86 and 90 percent.

There were savings of about 3 kgs per tyre and an unprecedented quantum jump in the tread life, allowing huge cost savings as well as safeguarding environmental interests and fuel conservation. In the mid 90’s it was estimated that one years new cars in the US saved more than 75 million litres of petrol just from the radials’ reduced friction. Most producers at that time however grossly underestimated the demand pull that introduction of radial tyres created.

Can we draw parallels to similar innovations taking place in today’s market, which have the potential to create more than just a ripple of passing interest but are yet to make their impressions felt in the industry? To help you decide, we recapitulate the factors that inspired the switch to radial tyres:

Longer tread life: Managed largely by reduction in operating temperature.

Fuel savings: Direct saving due to reduction in rolling resistance and indirect savings by way of reduced fuel at manufacturing stage.

Better steering quality: Mechanically stable side wall profile and a strong layer under the tread.

One such change quietly taking its place in the markets worldwide is the use of nitrogen in tyres in the place of normal air. All the arguments favoring and against this practice notwithstanding, the following points are worth spending a few moments over:

Compressed air normally available in India and elsewhere almost always has moisture and in cases where the dehumidification in the line is not carried out, actually sprays a fine mist of water along with air. It is an established fact that moisture with oxygen and aided by heat speeds up the ageing process of rubber.

Further the same moisture in the air corrodes the wheel surface in contact with it (more acute in the case of tubeless tyres) releasing fine rust particles into the tyre cavity. Fine rust particles are known to get caught in the valve seating during pressure measurement using a guage, while sucking in a small quantity of air to measure. Leakage that gets initiated at this point is slow but sure to gradually reduce pressure in the tyre and that too in an unbalanced manner across the vehicle.

Different pressures in different tyres of a moving vehicle are bound to end up with the owner forced to spending more on fuel.

When we realize that the repercussions of this discussion revolves around an industry which is responsible for 5% of the nations GDP, even a fraction of a percentage saved in fuel will have a huge cascading effect in the net fuel import bill of the nation.

If the field studies are any indication, savings in the range of 20% to 25% on tyre life have been reported with the use of nitrogen in tyres. Factor in the truth that tyre bills account for 5% of the operational expenses of a transporter, and we are probably sitting on a potential savings of few billions of rupees if the application is adapted extensively in India.

The best part of the attraction of such a technology, especially for a developing economy like India, is that the running costs of a nitrogen gas generator is practically negligible in comparison to the potential savings that its use is bound to fetch to the user. We at KKTC feel that the time is just ripe for India to be embracing extensively the use of nitrogen, as was the case in the US during the late sixties with respect to the acceptance of radial tyres. Shouldn’t we be creating history now and not having to repent later when it may be too late to correct things. We invite you to think over this – the beneficiary is convincingly the entire nation and we owe it to this great country at this stage.


Automobile tyre – How many of us, including some who claim to have a strong technical bend of mind, have paused to give the functioning of the innocuous car tyre of our daily use a second thought? How is it that a tyre filled to 28 psi, when fitted to a car weighing nearly a ton of weight still maintains the same pressure of 28 psi? The answer lies in the very complex engineering roles that the materials have been designed to perform. The air inside a tyre is not intended to carry load; but acts as a tensioning member. The numerous fibers that constitute the ply act like cables in a suspension bridge and carry the load of the vehicle; the role of air is only to keep these load bearing fibers in tension.

Market Watch

India – The Dream Destination for Auto Majors – The big daddies of haulage are all in the country with their own plans of establishing their presence, in scales and functions reflecting individual organization’s business conservativeness or bullish outlook. Hino is known to have closed in on Panipat to start manufacturing their hugely successful range of medium heavy vehicles. Scania with L & T, AMW by themselves, Mercedes enhancing their presence with the addition of buses and haulers are all at various stages of project implementation – some to cater to the Indian population while others hope to leverage export benefits in addition to sales to the local market.

From a country having less than 10 automobile manufacturers enjoying a virtual monopoly twenty odd years ago to the present age where close to 50 world class manufacturers are vying for the attention of this huge populace, making world premiers in India and in some cases even before the models are debuted in Europe, we sure have come a long way. The healthy fall out of this development is that other industries connected to this have also been active to keep pace. Trailer market in India grew at a rate of 40% from 32,000 units to 45,000 units in 2006 – 07. Consumerism driven retail boom and shopping malls have contributed to the need to have special purpose vehicles like refrigerated containers as well as a massive requirement for the one tonne delivery vehicles to cater to the ‘last mile delivery’.

That the customers in India are a growingly discerning lot is a healthy development, with in depth knowledge and exposure to technologies available world wide. He is also willing to pay a premium for a perceived extra feature as long as it delivers tangible value for money or maybe even if it fetches him a tag of exclusivity. Turf wars over possible intellectual rights infringement between Indian companies in the auto industry was unheard of till this month. UB baron taking over a F1 team has had the entire world sit up and take notice of a ‘no more quiet’ revolution happening.

In the immediate future, be prepared to see the onslaught of major technological improvements in the heavy commercial vehicle segment. Air suspension, ABS system, modular ………………, automatic tyre inflations systems etc. are all bound to change the way that we earlier were used to transporting goods from point A to point B. And all this makes for interesting reading as the moghuls of transport industry slug it out.

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