Euro 7 is a major focus at this year’s Tire Technology Expo Conference, which will feature a day-and-a-half of content on tire road wear particles starting tomorrow, March 5. Senior technical executives from tire manufacturers and industry bodies will present their latest research and discuss the requirements of the new legislation as the regulatory landscape continues to evolve.
At 14:25 on Wednesday, in the Analyzing and mitigating TRWP: implications of Euro 7 session, Dr Hiroshi Mouri, a rubber consultant and former Bridgestone executive, will present a new tire emissions collection method developed in partnership with Ueshima (Booth C400). The project, which began last year, aims to improve the accuracy of TRWP (tire and road wear particle) collection.
Mouri explained, “We used to collect TRWP using a vehicle on a road, which results in a mixture of particles. It’s not a clean study; in the lab, we can do it without contaminants. Ueshima developed this machine from scratch, and it uses an electrostatic collection method, which can collect particles down to submicron levels.”
It’s clear that the industry is seeking consensus on a standardized testing method. As Mouri noted, tire manufacturers currently favor a variety of techniques. He elaborated, “It’s a famous story that still exists. Michelin’s method collects all kinds of TRWP. Bridgestone’s indoor method simulates the tire on a vehicle on an indoor test machine, and it’s not always representative of the real world. Outdoors you have wind which you do not get indoors and you don’t pick up road or brake dust like you do on a vehicle, so all test methods have their pros and cons, but personally I think Goodyear’s is best.”
At 15:45 during the same session, Prof. Günter Leister, CEO of TWMS Consulting, will present alongside Kokusai on the latter’s new indoor tire abrasion test system. The system uses sandpaper and builds on the indoor method developed by JATMA. The core idea behind the JATMA test is to replicate real-world wear conditions in an indoor setting while refining the measurement process. Kokusai has taken a similar approach, focusing on improving the consistency of test surfaces.
One key challenge is the rapid change in the drum surface as more tires are tested, leading to varying abrasion levels. To address this, reference tires are required to maintain consistency. “Indoor testing didn’t normally need a reference tire for every test, but this is something we realized needed improvement,” Leister explained.
The solution is to maintain a consistent surface wear level for each tire. This is achieved by replacing one segment of the drum with fresh sandpaper before each test. This approach ensures consistent sandpaper quality, allowing for more stable reference measurements. As a result, reference tires only need to be measured once a month instead of before every test.
Currently, five or six suppliers are developing machines, and the focus of this study is to refine the testing methods. While sandpaper is one option, Leister noted that asphalt could also be considered, though centrifugal forces make this difficult to use in indoor testing. Finding a reliable artificial surface is an industry-wide challenge, he emphasized.
“The task today is to make the sandpaper method as good as possible,” Leister highlighted. There is already a one-position testing system in place, and work is underway on a two-position tester.
“The EU Commission aims to reduce microplastics by 30%. The task force is working on the percentage limit for tire emissions to achieve the goal. However, some simulations suggest actual levels may be significantly higher than expected – possibly exceeding 50% of tires nowadays, which will not be possible. This raises important questions: Is the target realistic? How should the industry engage with the EU Commission? Should auto makers be involved in discussions about their role in addressing the issue?
“At the moment we are only discussing tires, but next we need to consider the road because 50% of these microplastics is the road. We measure the mass loss of the tire, but we have to realize that the road has the same amount of mass loss.”
Asked for his thoughts on the various techniques for measuring tire road wear particles, Leister said, “The outdoor test clearly aligns more closely with real customer behavior. To ensure consistency, the test is conducted in areas with minimal traffic, avoiding red lights and stop-and-go situations. But without question, the outdoor test is the reference standard.
“The current method could see some minor improvements. Personally, I’m not a fan of mixing different car manufacturers or models in a convoy, but I understand it’s a necessary compromise to balance workload and efficiency. Typically, other tests only allow the same vehicle types, but the current method permits mixed vehicles.”
This raises some questions, but the task force has determined that the error margin is acceptable, meaning outdoor testing remains a viable approach. However, indoor testing still needs improvement – particularly regarding the sandpaper surface, which should be a key focus in the coming months, believes Leister.
“Right now, the correlation between indoor and outdoor testing is poor. Indoor results fall below the required standards, making them difficult to rely on. However, we know from tire manufacturers and Kokusai that achieving high repeatability is possible. That’s why collaboration with the task force is essential to improve indoor testing.”
Looking ahead, in three to five years, Leister stated that he believes indoor testing will likely become the norm to meet the additional analysis requirements without generating excess traffic. “However, this shift can’t happen without proper correlation – since outdoor testing is the reference, indoor results must align. If they don’t, we have work to do.”
The EU task force on tire abrasion is responsible for defining both the testing methods and limits, and ensuring a reliable transition.
Click here to read about the testing ramifications of Euro 7 in the November issue of ATTI.
Look out for a feature on Euro 7 exploring the latest updates in brake emissions analysis technology in the March issue of ATTI.
To find out more about the conference, click here. For more expo news, click here
