For the last 20 years, Michelin has been committed to reducing tyre abrasion and to research on wear particles
As tyre wear particles become an environmental concern. In many places tyre and brake emissions are now higher than exhaust emissions. The tyre industry has been faced with the challenge of reducing tyre wear. Michelin has now released news about their own research into tyre wear particles, the results of which may lead to more abrasive resistant tyres and a biodegradable tyre wear particle.
With a wish to reduce tyre abrasion and deepen knowledge in this field, Michelin has developed a system for analysing small, emitted particles, “SAMPLE”. This captures, sorts, counts and characterises particles in close proximity to tyres with unequalled precision and reproducibility. This analysis system, which was presented at Tire Technology, opens the way to the design of biodegradable tyre wear particles.
There are important questions being raised about tyre and road wear particles. To help answer these questions, it is essential to have reliable, reproducible and standardised measurements. This will be a fundamental step in better understanding the environmental impact of wear particles and in the innovation of new solutions.
Tyre wear particles are on average the size of a human hair (100 µm) and form a complex mixture composed of equal parts of tyre rubber (50 per cent) and minerals plus other road components (50 per cent).
The Michelin study has quantified the number of these particles that contribute to atmospheric pollution, i.e. PM10 and PM2.5 also known as fine particles. Until today, these figures had never been verified by such precise experimental measurements. The initial results show that among the particles emitted by tyres, on average 1.3 per cent are PM10 and 0.16 per cent are PM2.5, liable to be found in suspension in the air.
This precise quantification is important both for Michelin to increase understanding of the links between the tyre, the road and the driving style and also for the official bodies in charge of estimating city pollution. The data is essential to the design of simulation models for measuring air quality.
In December 2022 and in March 2023, this study was the subject of two scientific articles https://www.researchgate.net/profile/Frederic-Biesse. Finally, Michelin has made available this system for analysing emitted light particles to the tyre industry and to ETRMA (European Tyre & Rubber Manufacturers’ Association). ETRMA will now conduct a campaign of measurements on a larger scale with the aid of an independent third party. The campaign will launch this year and will continue for around 18 months.
Michelin’s approach is complementary to the Euro7 standard
The Euro7 standard that has just been adopted by the European Commission will shortly set down the regulatory tyre abrasion thresholds in order to reduce the quantities of particles emitted in Europe. This regulation has its own test method for quantifying all the wear particles from tyre and the road, in terms of grams per km per ton carried. It enables overall emissions to be measured on a very large scale for all tyres on the market. Those not meeting the standard will no longer be marketable.
Michelin, a long-standing advocate of this regulation, is engaged in a complementary approach, furthering its understanding of this issue.
Since 2005, numerous research and development facilities have been committed to a better understanding and reduction of wear particle emissions. To achieve this, Michelin relies both on its knowledge of materials and on a design strategy historically oriented to optimise the use of materials. This policy secured a 5 per cent reduction in wear emissions of Michelin tyres between 2015 and 2020 which has since continued.
At the end of 2023, the Group announced the creation of a common laboratory with the CNRS and the University of Clermont Auvergne: “BioDLab”. Its mission is to understand the biodegradation of wear particles, for then to develop tools for finding new tangible solutions to make them capable of being bio-assimilated.
The Clermont manufacturer is moreover internationally recognised as a leader in the field of particle emission longevity. A position confirmed by a test carried out by ADAC, the German automobile association (Study published in March 2022) on a hundred or so tyres.
Through these actions, Michelin wants to better understand the phenomenon of tyre wear particles and their degradation. There are multiple objectives: reduce their emissions, provide scientific responses, and develop technical solutions.
