Michelin, one of the world's largest tyre manufacturers, has long argued that wear is not the only factor that matters for safety. In support of this position, it has produced numerous tests that would demonstrate how greater tread depth is not necessarily synonymous with greater safety. But let us try to understand. For a car, tyres are the connection with the road; our safety, comfort, even fuel consumption and, to a certain extent, a car's emissions all depend on their condition and characteristics. Not many people know it, but for years a specific label applied to tyres has indicated very important parameters, such as rolling resistance, noise levels and, again, wet braking. These are certainly important values for anyone who needs to buy a new set of tyres.

Yet the kilometres covered and the time elapsed since fitting (a tyre ages and deteriorates even when stationary, especially if the car is left standing for a long time) are factors that are often overlooked, feeding the false myth that a car's "tyres," and their initial characteristics, last forever.

To prevent this from happening, and in support of greater awareness of and attention to road safety, Michelin is working to bring about the introduction of a series of regulations that, exactly as is the case for new tyres, would also define rules for worn ones, so as to establish a minimum standard to be met. This would give the end user a clearer idea of the product they intend to purchase, but above all would provide the assurance of having chosen a tyre that remains safe over time.

Why, and how, tyres change as they age

When people think of a worn tyre, they typically think only of the minimum tread depth value, also required by law, of 1.6 millimetres. To verify that this limit has been reached, a block is set into the groove in line with the marking on the tyre sidewall known as the TWI, Tread Wear Indicator. In practice, this is the wear limit to which tyre manufacturers should refer in order to guarantee reasonable safety conditions.

Yet in practice there is no regulation that defines performance standards during progressive wear — that is, as one approaches the limit imposed by law. The reason is that current rules tend to consider only new products.

Whereas from the moment a new tyre wears progressively, its performance profile changes, sometimes considerably in certain respects.

Some characteristics improve, such as braking and grip on dry asphalt, rolling resistance and noise levels, while others are heavily influenced by the state of wear. This is a very clear picture for Michelin which, precisely in the interest of the safety of its own products, has long been pushing for parameters to be set not only when discussing new tyres, but also when it comes to worn ones — which, if you think about it, actually represent the most common situation on our roads.

How wear also impacts sustainability

Long Lasting Performance by Michelin. This is not a slogan, but rather the working approach of the French giant, which is measured not simply by the quality of its products, but by a modus operandi in defence of the consumer. This method puts into writing the reflections just described. And while safety certainly represents one of the main pillars — because it refers to products that remain safe over time — sustainability also plays a leading role.

If the performance of worn tyres were also regulated, consumers would know with certainty when the time had come to change their set of tyres, without replacing them ahead of schedule (or worse, too late). Having this type of information would make it possible to reduce waste. And reducing waste and consumption can also have significant environmental implications, supporting the sustainability of the tyre's lifecycle. In this way, the consumer would have all the information needed to make an informed choice.

Michelin and the scientific proof of its theories

Michelin's considerations obviously carry scientific weight, being the fruit of in-depth testing. Above all, the French manufacturer is campaigning for the same testing methods applied to new tyres to be applied equally to worn ones — methods that Michelin is pushing to have replicated at an institutional level as well. In short, a genuine campaign for road safety.

One of the tests that would carry great weight on the question of "wear" is the wet braking test, carried out in such a way as to measure the distance a vehicle needs to decelerate from a speed of 80 km/h to 20 on a road surface covered by 1 millimetre of water. This is one of the most common road situations, one that all of us have encountered countless times. And it is precisely on this point that the French group has long been campaigning — namely, for this test to be made compulsory for worn tyres as well, and not only for new ones.

The approach that Michelin calls Long Lasting Performance makes it possible to produce reliable products over time — that is, products capable of consistently guaranteeing a high safety standard even when worn, because they are not designed to "perform" only when new. So much so that during a test in September 2018, at the Papenburg circuit in Germany, a car fitted with worn Michelin tyres braked 3.4 metres shorter than the same car equipped with new but lower-quality tyres.

Tyres, the three benefits in favour of performance built to last

What benefits could be gained if everyone used tyres tested not only when new, but also at the end of their life, without therefore replacing them prematurely as sometimes happens? According to Michelin, the possible benefits would be at least three.

• Increasing customer safety by providing them with relevant information about the performance of their tyres, both new and worn. The need to inform motorists about worn tyre performance is all the more justified by the fact that how that performance evolves over time is a choice made by the manufacturer and its investments.
• Improving the ecological footprint of the entire tyre industry through production savings that could reach 128 million tyres per year in Europe and a reduction in CO2 emissions of up to 6.6 million tonnes, as found in the study carried out by Ernst&Young in 2017 entitled Pas de fatalité à l'obsolescence programmée.
• Increasing consumers' purchasing power, with savings for European motorists of up to 6.9 billion euros every year.