Editor-at-large Alex Grant considers the debate around tyre particulates – and how much attention fleets should be paying to this discussion.

FW editor-at-large Alex Grant

The UK hasn’t fallen out of love with the convenience of road transport just yet, but it’s taken some serious reputational damage recently. After a decade of high-profile crises around efficiency and air quality, the bad news can feel relentless at times, but it’s not always unjustified. As technology leads us towards cleaner powertrains, the impact of non-exhaust emissions – especially tyres – are coming under ever-closer scrutiny and it’s a debate fleets should be watching closely.

Concerns about tyre and road wear particles (TRWP – a bonded 50/50 mix of materials from the tyres and the road surface) are nothing new. The manufacturer-backed global Tire Industry Project (TIP) was formed in 2005 to start filling knowledge gaps and the European Tyre and Rubber Manufacturers’ Association (ETRMA) formed its own working group in 2018. At an industry level, the goal is to develop standardised testing methods, identify what influences abrasion rates and then either mitigate emissions at source, or capture material nearby.

The potential scale of this issue is certainly headline worthy. In 2019, the UK’s National Atmospheric Emissions Inventory claimed that brake, tyre and road wear accounted for 73% and rising of PM10 (fine) and 60% of PM2.5 (ultra-fine) and road transport particulate emissions – the latter capable of getting into our bloodstream and lungs. A year later, government-funded research at the University of Plymouth concluded that TRWP is also one of the biggest sources of marine microplastics, having been carried to sea by storm drains.

However, it’s the 2020 study by Emissions Analytics that’s perhaps become more notorious, although mostly due to misinterpretation. The independent laboratory set out to simulate best and worst-case abrasion tests, as a baseline indication of how driving style and vehicle weight influence particulate emissions. At worst (and, by their own admission, an exaggerated case) the results suggested the latest RDE2 compliant cars could be emitting 1,000 times more particulate matter from their tyres than at the tailpipe.

The resulting media frenzy, and Commons discussion, focused on the implications for our reliance on usually heavier electric vehicles to reduce our transport emissions. Few outlets paid much attention to the wider issue raised about vehicles getting heavier across the board – most SUVs still have tailpipe emissions to think about.

Emissions Analytics has since stressed that driving style can counteract the effects of EVs’ additional weight and has begun classifying tyres by the toxicity of their component materials. If the latter sounds like a niche interest, bear in mind that California recently proposed controls on a substance called 6PPD, used to stop tyres hardening, having discovered that waterborne tyre particulates were killing salmon and trout. A potential precedent for other markets?

Solutions will take time. Tyres are safety-critical and inevitably shed material as they wear and the industry is focusing on what happens afterwards. Goodyear revealed a biodegradable tyre in 2020, while Michelin and Continental are integrating organic materials into new products and prototypes. In Germany, the Audi-funded Urbanfilter project is testing roadside filtration systems, which can be adapted to suit weather and traffic conditions.

Fleets can take steps in the meantime. Encouraging better driver behaviour – including regular pressure checks – can help. And there’s data to support more informed procurement too. German motoring association ADAC is ranking tyres by particulate output, showing the best performers shed half as much material as the industry average, while the worst emit 50% more. With the buying power to influence further innovation – and the operational scale to make emissions reduction worthwhile – fleets should definitely be watching this one closely.