Wearing down tyre emissions

The amount of particulate material which comes out of an exhaust pipe of a car is relatively modest compared to what is abraded from its tyres.

While there has been a substantial decrease in exhaust emissions over the last 30 years in the UK, non-exhaust road emissions have remained consistently and undesirably high over the same period, as evidenced from a 2023 national statistics report.

Efforts over the previous decades have predominantly concentrated on reducing exhaust emissions to meet the strict emissions standards. Now, the focus is starting to shift to address the largely neglected aspect of non-exhaust emissions.

For the very first time, a new Euro 7 emission standard will impose a minimum standard for non-exhaust emissions. With this standard soon to be introduced in 2025, the stage is set for tyre manufacturers to improve their technology in the quest to reduce urban pollution arising from tyre wear, preferably without significantly compromising performance. 

EV particulates in particular

Non-exhaust emissions include particulates which are released into the air from abrasion of the vehicle components with each other or with the road, such as from brake wear, tyre wear and road surface wear. After single-use plastic, tyre particulates constitute the second largest source of micro-plastics in the environment, and so are inevitably accompanied by a myriad of environmental and health concerns (see our earlier blog Tyres: the secret polluter). Crucially, the amount of particulates from tyres can be over 1000 times higher than those from exhaust gases.

Tyre particulate generation is further amplified by electric vehicles (EVs) in particular. Being inherently heavier than their petrol and diesel counterparts, this naturally leads to an increased abrasion of the tyre with the road, thereby accelerating tyre wear by 20 to 50%. Needless to say, it is a somewhat paradoxical notion to encourage the use of EVs, which advantageously have zero exhaust emissions, and yet particulate air pollution may be caused to increase.

Now, with EVs becoming increasingly ubiquitous in our society, and to meet the incoming Euro 7 emission standard, the need to wear down the historically high emissions from tyres becomes more vital than ever.

ENSO Tyres

In the drive to tackle tyre wear, London-based electric vehicle manufacturer ENSO is developing sustainable tyres exclusively for EVs to achieve more efficient and eco-friendly performance.

The performance of these tyres is improved with a more durable tyre tread with lower rolling resistance, which translates to reduced energy consumption for the same distance travelled, thereby accessing increased driving range. ENSO reports that their tyres wear more slowly because they use higher grade raw materials and are specifically designed for use with the heavier, battery-laden EVs.

In particular, the treads of ENSO’s tyres employ stronger and more flexible elastomeric networks, incorporating compounds having self-healing properties which reduce and heal breaks in polymer chains. This helps significantly in the reduction and suppression of microcrack formation in the tyres. The consequently slower rate of wear of these tyres reduces the overall amount of particulate emissions over time.

Furthermore, as these tyres are recyclable, they establish a circular economy process for EVs. In this connection, ENSO partnered with energy giant Wastefront, who is currently constructing a £100 million tyre recycling plant at the Port of Sunderland, to establish a recycling outlet for its used tyres. Not only would this contribute to the reduction of end-of-life tyre waste, the recovered materials, such as carbon black, may be repurposed in the manufacture of new tyres (see our earlier blog Circular tyres: a new challenge for the circular economy).

Advantages all-round

To demonstrate the effects of their innovation, ENSO partnered with Royal Mail and DPD to incorporate their tyres onto electric vans operated by the two delivery companies as part of a performance test trial in 2021. During this trial, the tyres were monitored and weighed every six weeks to measure their wear rate, estimated particulate matter emitted and range achieved, and then comparing these results against standard tyres.

Following the trial, it was reported that the ENSO tyres had outperformed the standard tyres both in terms of reducing particulate emissions by up to 35% and improving energy efficiency by up to 10%. The success of the trial has been further validated by the Royal Mail, who will publish later this year a report of a second phase of the trial.

In another separate test, ENSO reported that the range of a Renault Zoe, modified only by incorporating their tyres, was extended by 50 miles (around 12%) compared to one using standard OE tyres.

A circular economy business model

In addition to the tyres themselves, ENSO is also adopting a circular economy business model. While the traditional tyre industry arguably incentivises sheer volume of tyres sold, ENSO seeks to supply directly to its customers on a pay-per-mile basis, essentially providing their tyres as a service rather than a product per se.

According to ENSO CEO Gunnlaugur Erlendsson, the service “reduces total cost of ownership while helping to manage cash flows”, the latter of which is driven by Zeti’s fintech platform to monitor and gather real-time data for pay-per-mile billing calculations.

With this approach, ENSO seeks to profit from the improved durability of its tyres and to take advantage of their extended lifespan, thereby creating a strong financial incentive for continuous innovation in this space.

Meeting the standards

The Euro 7 emission standard will eventually need to be complied with by all tyre manufacturers looking to supply into the European market. Indeed, ENSO is not the only manufacturer who has steered towards meeting this regulation. For instance, Bridgestone demonstrated reduced tyre rolling resistance by up to 20% when applying their own lightweight tyre technology.

As the electric vehicle market is continuing to grow rapidly, there is significant opportunity for all tyre manufacturers, whether they are an SME such as ENSO, or a global manufacturer such as Bridgestone, to deliver tyres with significantly reduced emissions, in terms of particulate volume, size and toxicity.

While ENSO themselves have not yet disclosed any further details of their new tyres, we will undoubtedly look forward to seeing future developments and associated IP to meet the challenge of the Euro 7 emission standard by 2025.