electric charging Prius plug-in hybrid close up

The RAC has refuted suggestions made by a government minister that electric vehicles produce more harmful polluting particles from brake and tyre wear than their petrol and diesel counterparts.

Environment secretary George Eustice told MPs on the Commons’ environment, food, and rural affairs committee that fine particulate matter known as PM2.5 may be worse with electric cars due to them being heavier.

Eustice told the committee: The unknown thing at the moment is how far switching from diesel and petrol to electric vehicles will get us. There is scepticism. Some say that just wear and tear on the roads and the fact that these vehicles are heavier means that the gains may be less than some people hope, but it is slightly unknown at the moment.’

RAC commissioned battery electrochemist Euan McTurk to address these remarks.

In his report, McTurk stated most of the braking in electric cars was done via regenerative braking where the electric motor works in reverse, converting kinetic energy from the moving vehicle into electricity to charge the battery when slowing down.

He argued this would reduce the use of the mechanical brake discs and pads and therefore EVs brakes wear more slowly than conventional cars.

He said: “Dundee Taxi Rentals says that brake pads on its 11 Nissan Leaf taxis have a lifespan of 80-100,000 miles – four times that of their diesel taxis,” he says. “Discs tend to be changed due to warping rather than wear unlike a conventionally fuelled vehicle, and last twice as long as those on diesel taxis.

“In addition, Cleevely EV, one of the best-known EV mechanics in the UK based in Cheltenham, regularly sees EVs with brakes that have lasted over 100,000 miles. The company says if they ever need to replace an EV’s brakes, it’s not because of wear but because they’ve seized up due to lack of use.”

In terms of tyre wear, which is another source of particulate matter pollution from any vehicle, McTurk disputed the widely quoted research carried out by Emissions Analytics (EA) in 2020 which concluded pollution from tyres was 1,000 times higher than a car’s exhaust emissions.

Dr McTurk said: “An Emissions Analytics 2020 press release stated that a car they tested shed 9.28 grams of particulate matter per mile from its tyres. However, it turns out that this was a worst-case scenario featuring the cheapest tyres, heavy ballast in the car and driving at high speeds with much cornering. This point which wasn’t made clear in the press release, which was subsequently reported extensively in the media.” 

A typical family car tyre weighs around 9kg, giving a total weight of 36kg. If a car shed that much particulate matter its tyres would physically disappear in less than 4,000 miles and the car would be running on its alloys.

“In reality, tread represents about 35% of a tyre’s total weight, so the tyres would be bald in less than 1,358 miles, or two months’ of driving for the average UK driver.”

His report also stated that EVs don’t get through tyres as fast as some claim due to their weight. British Gas, which currently operates 800 pure electric vans, reported that its latest large, heavy electric vans have done 15,000 miles and have not yet needed replacement tyres.

RAC EV spokesperson Simon Williams said: “George Eustice’s remarks about EVs not being as green as some may think were very unhelpful and could put some drivers off making the switch to zero-emission driving. There are far too many negative myths surrounding electric cars which need to be busted as soon as possible in order to speed up the electric revolution. We hope these positive real-world experiences will help to clear up some of the confusion.”