Tyre technology: Tread carefully now

Michelin has invented a tyre that creates new grooves as it wears. Trucks benefit first, and private cars may be next
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Indy Lifestyle Online

Like me, you probably don't think about tyres much. I'm not one of those drivers who can pick up all sorts of subtle differences in a car's behaviour depending on the precise brand and type of tyre fitted; at least, not on normal roads in normal conditions. The only time I can remember tyres being an issue was when BMW decided to do away with spare tyres and start fitting its cars with run-flats, which gained a reputation for harshness. Even that fuss faded, presumably as refinements to the tyres and cars reduced the problem.

Michelin, though, has now come up with a set of tyre innovations, called "Michelin Durable Technologies", that may get everyone to sit up and take notice. The company believes the improvements (at present available only for its truck tyres) are as significant as the invention of the radial.

So what precisely are these Durable Technologies? One, called Infinicoil, consists of a single-piece 400-metre-long steel cord wrapped around the crown of the tyre. It produces a more rigid tyre with longer tread life and greater load capacity; in some cases, a pair of truck tyres may be replaceable with a single tyre. One application is the front tyres of car transporters, where these stronger tyres allow heavier loads to be carried over the cab.

The surface of the tyre is also improved, in particular the sipes - those narrow slits that complement the much larger grooves of the tread. A new sipe design - the double-waved sipe - makes the tread block more rigid, helping to reduce wear.

The really clever innovation, though, which is at the heart of tread regeneration, is the raindrop sipe - so called because in cross-section it has a raindrop shape. As the tyre wears, the fatter part of the sipe below the initial tyre surface is exposed. This forms new, additional main tread grooves, boosting grip levels in worn tyres. Tyres with these new technologies can be retreaded - a standard procedure for truck tyres - as well.

Not all of Michelin's truck tyres will incorporate all of the new technologies, but one that does is the Michelin XDN 2 GRIP. At the company's test-track at Clermont-Ferrand in France, I was able to see the improvements at work. First, an articulated lorry with worn standard tyres on its drive axle attempted to negotiate a soaked circular track. Even Michelin's skilled test-driver had difficulty avoiding jack-knifing at little more than 20kph, but when the tyres were replaced by a pair of XDN 2 GRIPs with a similar degree of wear, the truck could corner far more quickly without any drama.

Another test, involving two light trucks on the wet circular track, was equally convincing. Although the vehicles started at opposite sides of the track, the truck fitted with the improved tyres quickly caught up with the one that was not.

It's not just road safety and operating economics that are at stake here, but British jobs too. Michelin has 20 truck-tyre factories around the world, and at first, only five will be making tyres with the new technologies. Its UK plants at Dundee in Scotland and Ballymena in Northern Ireland are not in this initial group, but Pete Selleck, an American who heads Michelin's world truck-tyre activities, says that "after the initial wave of €400m of investment... we would anticipate that we would then add additional investment blocks in most of our plants".

What most of us want to know is when Michelin's car tyres will feature these new technologies. The company hasn't made any announcements, but it's clear the subject is a live one. It's not just a technical question - there are car owners' buying habits to consider.

Haulage companies monitor the costs and performance of parts very closely because their livelihoods depend on it; such buyers can be persuaded to pay more for a tyre if it can be shown that the extra cost will be more than offset over the life of the tyre by better wear performance and improved safety. Car owners, by contrast, tend to ask either for the cheapest tyre or, to be on the safe side, a like-for-like replacement. That makes it more difficult for an innovative tyre to make headway, at least in the replacement market. But make no mistake; you'll hear more of Michelin's self-regenerating tyre treads.

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