Whoops
Emissions Analytics are an outfit that, as their name implies, analyses emissions. They were in the news six years ago when they showed that emissions from diesels were worse than we thought. They also measured real-world fuel economies and found that they were worse than advertised.
Searching Google News shows that the Guardian picked up the diesel emissions story. It has not yet picked up Emissions Analytics’ latest “worse than we thought” emissions story, or if it has, Google is not aware of that fact.
If that omission surprised a jaundiced climate cynic, his raised eyebrows probably settled back to their accustomed lodgement when they read the new headline from Emissions Analytics:
Gaining traction, losing tread
Pollution from tire wear now 1,850 times worse than exhaust emissions
Emissions Analytics, wisely diversifying into non-exhaust emissions from surface vehicles, found in 2020 that particulate emissions from tyre wear now dwarfs that from (new) engines.
On the one hand, we have the improved filtration unit on diesel cars:
Filters are so good that we have measured that in certain circumstances, when the ambient air is already polluted, a diesel car will tend to extract more particles from the air than it emits.
Not something that I would have predicted.
On a polluted day where ambient concentrations of particles are already high at 50,000 #/cm3, the vehicles remove on average 27,984 particles per second of operation.
[They still pollute on clean-air days.]
At the moment it sounds as if new diesels could be described as mobile air filtration units. As particulates concern me far more than CO2 emissions (which don’t concern me at all in fact), this sounds like a big tick for diesels.
On the other hand, tyre wear is surprisingly high:
Driving a 2011 VW Golf 320kms at high road speeds on the track resulted in a mass loss of 1,844g which equates 5.8g per km. This was 29 times worse than our hypothesis, and partly explained by our deliberate quest for a ‘worst case scenario’. It should be noted that the driving and vehicle payload would be aggressive but legal if conducted on the public highway.
The mass loss from tyres was >1000 times higher than permitted particulate emissions from exhausts:
Nevertheless, it is a very high figure: 5,760mg/km of completely unregulated tyre wear emission versus regulated exhaust emission limits of 4.5mg/km – a factor of over 1,000.
Yea, I hear you cry, but these are big lumps and are not remotely comparable to the smoke coming out of a diesel. You probably have in mind the tracksides after an F1 race. And yes, most of the mass lost falls straight to the ground. But:
…the tyre wear emissions also included a high number of particles down to 10nm, as a result of volatilisation of the tyre material due to heat in the tyres. Therefore, tyres shed material that both leads to microplastics in the watercourse, and ultrafines that compromise air quality.
That was 2020. In 2022, Emissions Analytics have revisited tyre wear.
They note that their previous work had made electric vehicle drivers a little twitchy:
Particularly vocal were the battery electric vehicle (BEV) community, sensitive to any suggestion that the added weight of these vehicles might lead to tire wear emissions that might confound the ‘zero emissions’ tag. Such was the reaction, the story was translated into over 40 languages worldwide.
Now, in the first study they loaded up a golf and threw it around a race track to measure tyre mass loss – that’s because they were worried that if they drove it normally at low weight they wouldn’t be able to measure the mass loss. But in 2022, they report wear under “normal” conditions:
The headline conclusion we draw now is that, comparing real-world tailpipe particulate mass emissions to tire wear emissions, both in ‘normal’ driving, the latter is actually around 1,850 times greater than the former. Yes, in normal driving the ratio is almost double the previous figure for aggressive driving.
This seems counterintuitive, but:
Tailpipe emissions are falling over time, as exhaust filters become more efficient and with the prospect of extending the measurement of particulates under the potential future Euro 7 regulation, while tire wear emissions are rising as vehicles become heavier and added power and torque is placed at the driver’s disposal. On current trends, the ratio may well continue to increase.
Heavier… torque… power…
An image is forming in my mind…
Are they by any chance talking about cars that are carrying a little extra around the middle because they run on battery power?
Anyway, what was it I was saying the other day? A picture paints a thousand words? Here is their provided figure:
The bar on the left is mass loss from the 2020 Golf study. The next two bars are tyre wear from new or used tyres. The next is airborne (fine particle) emissions from normal driving on new tyres. Then we have the additional wear from +500 kg on the vehicle, then the legal limit for tailpipe particulates, then tailpipe particulates of new diesels. Note the log scale.
Tailpipe emissions are now 1/250th of the legal maximum. Airborne tyre wear on new tyres with normal driving already exceeds the legal tailpipe limit. So it’s not just lumpy bits.
…11% of the mass of tire emissions is smaller than 2.5 microns in diameter (defining the common metric for fine particle dust, PM2.5, which can be airborne). Therefore, the airborne tire emissions are more likely to be around 8 mg/km as shown in the table above – this is still more than 400 times higher than tailpipe emissions.
Emissions Analytics are now working on finding out what lovely toxins are present in these ultrafine particles.
I don’t think electric vehicle drivers are going to want to know. Will the Guardian?
Final point: these guys are engineers, so they probably know what they’re doing. Nevertheless, we don’t want to seize on data that supports our worldview just because it supports our worldview. Other groups need to replicate or refute this study before we start up the Muttley laugh.
But on this data, EVs could be the next CFT.
Climate Scepticism 
CFT? Consequence of Failure Type?
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Sorry Mark. There is a finite chance that I meant CFL. In any case I was referring to those little twisted lightbulbs that were being handed out in vast numbers a few years ago as better than incandescents, only to prove worse.
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Well, that *was* an interesting post, Jit. Thanks for sharing the info.
Perhaps Emissions Analytics could now be working on finding out what amount of particles there are from cars with ‘normal’ braking vs cars with an extra 500 kg mass and regenerative braking.
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The data filtration on the funny bone that triggers my Muttley laugh is by now very old. High five!
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The RAC seems to have commissioned a report to cast doubt on EVs being worse than diesel or petrol cars when it comes to particulates from tyres and brakes:
“Do electric vehicles produce more tyre and brake pollution than their petrol and diesel equivalents?”
https://www.rac.co.uk/drive/electric-cars/running/do-electric-vehicles-produce-more-tyre-and-brake-pollution-than-petrol-and/
“So, in conclusion, electric vehicles already vastly reduce particulate matter from brake wear, and claims of tyre wear contributing 1,000 times the particulate matter pollution of petrol and diesel exhausts are greatly overexaggerated. Real EV fleets are already seeing brake lifespans increased fourfold versus the diesel vehicles they have replaced, and tyre wear that is broadly on par with petrol and diesel cars (unless, as like with any vehicle, the drivers get a bit throttle happy!).
One final thought on emissions to end with: the UK is set to close its last remaining coal-fired power plants, but even if EVs were 100% powered by coal, it is much easier to fit particulate filters to a small number of very large, static power plants located away from city centres, than it is to fit effective filters to millions of small, mobile petrol and diesel engines running in urban areas.
The end result is that cities that have embraced EVs have already demonstrably benefitted from reduced pollution and improved air quality, and this trend shall only continue as more EVs switch to drum brakes, new tyres are developed that reduce nanoparticulate pollution even further, and the UK’s grid becomes ever increasingly powered by clean renewable energy.”
It was written by Dr Euan McTurk, and I am in no position to contradict his findings. It does read to me, though, a little as though he doth protest too much, and a quick internet search reveals that he has skin in the game:
“Dr Euan McTurk is an expert in electric vehicle charging technology. Based in Inverkeithing, he runs Plug Life Consulting.”
https://www.thecourier.co.uk/fp/business-environment/transport/2970129/relief-for-ev-drivers-as-perth-electric-car-charging-hub-to-open-later-this-year/
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Mark, I’m prepared to believe that Emissions Analytics’ claims are exaggerated. But McTurk’s commentary does appear to have a few holes in it. If EVs have comparable tyre wear to conventional vehicles, some magic has gone on with the extra 500 kg of mass. It is possible that having four-wheel drive reduces oversteer and consequently wear on front tyres as folk drive around roundabouts. But that should be balanced by reduced wear on free rolling wheels.
If new materials are going to produce better tyres, then such tyres could also be used on the lighter vehicles.
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Hi JIT – Interesting read.
TV ads – https://dieselemissionclaims.co.uk/ seem to be the latest “ambulance chasers” on diesel cars/vans/etc
from the site “What is the Diesel Emission SCANDAL?
Vehicle software cheated air pollution tests by adjusting the engine to emit less and make it look like a low-emissions vehicle, when in fact they were emitting dangerous levels of pollutants.”
“Vehicle software cheated air pollution tests” !!!
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Here’s the thing:
Tyre emissions are produced by wear on the tyre. Therefore to minimise the emissions wear has to be reduced. Hence the life of the tyre will increase, which suggests that the aim, therefore, would be a tyre which had, if not an infinite life, then one which matched the life expected of the vehicle.
I can’t see the tyre manufacturers being too happy with this prospect. I suspect it ain’t gonna happen.
Also, a tyre that minimises wear is likely to produce less grip, which would raise other safety concerns.
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Bill, I think you are right in that there will be a tradeoff between durability and grip.
On the other hand, if you want to change the velocity of a car then the force acting where the rubber meets the road is proportional to the mass of said car, so presumably lighter cars have lower tyre wear, which is what Emissions Analytics is getting at. You could also reduce the scale of velocity changes. As an example, in our dystopian future where every car is tethered to the one in front by some automagical device, then those compression waves we see on motorways could be eliminated. Even replacing roundabouts with crossroads could help by reducing cornering speeds. And of course reducing speed limits would naturally decrease tyre wear. I’m not advocating any of these things because I’m still at the stage where I can’t quite believe the data as have been presented. But I would like it if drivers in our fine city actually stuck to the presently prescribed limit, just to make it easier to cross the road.
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“Electric cars should face ‘tyre tax’, says air quality adviser
Particulates generated by tyre wear are more dangerous to public health than diesel exhaust fumes, a Government expert claims”
https://www.telegraph.co.uk/business/2022/05/30/electric-cars-should-face-tyre-tax-says-air-quality-adviser/
“A ‘tyre tax’ will need to be imposed on electric cars to combat poor air quality in cities, the Government’s top clear air adviser has claimed.
The chairman of the Government’s independent science advisory group on air pollution said charges for low-emission zones are likely to be replaced with alternative levies as drivers switch to electric vehicles.
Particles from tyre wear are more dangerous to public health than diesel exhaust fumes, Professor Alastair Lewis said.
Known as “particulate matter (PM) 2.5”, the amount of air pollution is growing because motorists are driving ever larger vehicles with more substantial tyres.
Professor Lewis said: “If you compare a modern Mini now with an old Mini, they’re almost unrecognisable in their size.
“[And] larger, heavier vehicles will generate more particles.”…
…Professor Lewis, also chairman of the Department for Transport Science Advisory Council, said: “When everybody owns a low emissions vehicle, low emission zones become a toothless control lever to try to manage air pollution.
“A world where we [have] jam-packed roads full of electric cars [also] isn’t a particularly attractive one… Even if they are electric, [they] will generate lots of particles.”
“At some point in the future when most of those cars have disappeared, a different form of air pollution control” is likely to be needed, he added.
“We do have to project forward about how we’re going to manage vehicles in large cities like London in the future when we have a largely electrified fleet of vehicles.”
Luke Bosdet, an AA spokesman, said he was opposed to the idea of any tax on an electric vehicle which would act as a deterrent to them replacing traditional petrol or diesel vehicles….”
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Thanks Mark. I had seen that story but hadn’t got around to posting it here. Seems I was wrong before – someone with the ear of power, and at least a part of the media, have noticed Emissions Analytics’ stuff after all.
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“Car tyres produce vastly more particle pollution than exhausts, tests show
Toxic particles from tyre wear almost 2,000 times worse than from exhausts as weight of cars increases”
https://www.theguardian.com/environment/2022/jun/03/car-tyres-produce-more-particle-pollution-than-exhausts-tests-show
“Almost 2,000 times more particle pollution is produced by tyre wear than is pumped out of the exhausts of modern cars, tests have shown.
The tyre particles pollute air, water and soil and contain a wide range of toxic organic compounds, including known carcinogens, the analysts say, suggesting tyre pollution could rapidly become a major issue for regulators.
Air pollution causes millions of early deaths a year globally. The requirement for better filters has meant particle emissions from tailpipes in developed countries are now much lower in new cars, with those in Europe far below the legal limit. However, the increasing weight of cars means more particles are being thrown off by tyres as they wear on the road.”
Being the Guardian it seeks to downplay the possibility that EVs might be worse than ICE vehicles:
“…The average weight of all cars has been increasing. But there has been particular debate over whether battery electric vehicles (BEVs), which are heavier than conventional cars and can have greater wheel torque, may lead to more tyre particles being produced. Molden said it would depend on driving style, with gentle EV drivers producing fewer particles than fossil-fuelled cars driven badly, though on average he expected slightly higher tyre particles from BEVs.
Dr James Tate, at the University of Leeds’ Institute for Transport Studies in the UK, said the tyre test results were credible. “But it is very important to note that BEVs are becoming lighter very fast,” he said. “By 2024-25 we expect BEVs and [fossil-fuelled] city cars will have comparable weights. Only high-end, large BEVs with high capacity batteries will weigh more.”…”.
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Mark, it is interesting that the Guardian has noticed this story. I must say I find Dr. Tate’s optimism very hard to believe. The mass differential between the Volvo XC40 ICE/EV as mentioned in “Slips the Green Halo” was given as: ICE 1690 kg and EV 2170 kg. That’s a difference of 480 kg, close to the Emissions Analytics’ used value of 500 kg.
Of that 480 kg difference, the battery accounts for 350 kg. I would expect that, exempting the battery, the EV would be lighter, but seemingly not.
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“Tyre dust: the ‘stealth pollutant’ that’s becoming a huge threat to ocean life”
https://www.theguardian.com/environment/2022/jul/25/tyre-dust-the-stealth-pollutant-becoming-a-huge-threat-to-ocean-life
“…Tyre-wear particles – a mixture of tyre fragments, including synthetic rubbers, fillers and softeners and road surface particles – are considered by environmental scientists to be one of the most significant sources of microplastics in the ocean.
Created during acceleration and braking, they are dispersed from road surfaces by rainfall and wind. The main environmental pathway is from road run-off into storm drains, where they empty into rivers and the sea. They are also released from sewage effluent and from the atmosphere, where they can circulate into the ocean and back again. A 2020 study suggested windblown microplastics are an even bigger source of ocean pollution than rivers.
While it is fiendishly difficult to pin down the exact composition of microplastics, there is plenty of research which points to tyre dust making up a significant portion.
In 2017, a global model by the International Union for the Conservation of Nature estimated tyre wear to be the second largest source of primary microplastics in the ocean, at 28%, after synthetic textile fibres, at 35%.
And, in 2019, a report by scientists across Europe concluded abrasion from car tyres was a large source of microplastics and possibly nanoplastics. While there remains a lack of data on risks to the environment and human health, the scientists concluded that if future emissions remain constant or increase “the ecological risks could be widespread within a century”.
One thing is certain. Tyre-wear particles are ubiquitous. The average tyre loses 4kg over its lifetime. About 6m tonnes of tyre particles are emitted annually and have been found everywhere from the deep sea, to the atmosphere, even in the Arctic and the Antarctic.
And it is only going to get worse. Electric cars will lower tailpipe emissions, but tyre wear is projected to rise, due to heavier vehicles and torque (the rotational force of a car engine). The UK’s air quality group warned in 2019 that dust from tyres and car brakes would continue to pollute the air, rivers and ultimately the sea, even when the fleet has gone electric….”.
All potentially true. However, I fear I know where this is going – ICE cars bad because of CO2 emissions. EV cars bad because of tyre emissions. Answer – we all have to give up our cars.
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Only slightly O/T, I think:
“Building works responsible for 18% of UK large particle pollution
Experts call for tighter regulation as construction accounts for more than 30% of PM10 pollution in London”
https://www.theguardian.com/environment/2022/oct/21/building-works-responsible-for-18-of-uk-large-particle-pollution
I dislike pollution as much as the next person, but I do worry that at this rate we’re not going to be allowed to carry out any useful activities at all, unless we do so in a completely impractical and expensive way.
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I would like to see some pollution surveys taken on fine summer days when the wind is southerly and all the cars parked along the roadsides become covered with fine red dust.
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The Sahara & Angle & other Grinders should be banned ASAP.
PS – “he London mayor has produced guidelines for large construction sites and has set minimum standards for the diesel-powered diggers, generators and machinery…..Daniel Marsh from Imperial College London…. clear regulatory pathway to reduce machine emissions as there are no standards or dates for new engine limits”
The madness just goes on. and what about wood burners this winter in London?
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Wood burners have been banned in most London boroughs for a couple of years. Even bonfires on allotments have been banned too.
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bill – “Wood burners have been banned in most London boroughs for a couple of years”
ok – never new that, so it’s gas or lecy heating in London?
thought Wood burners were the in thing a few year ago?
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“Delaying MOTs could spark a rise in the number of electric cars on the road with dangerously worn and damaged tyres, report says”
It = The Institute of the Motor Industry
The reply?
Not trying to spot a logical fallacy here, but presumably one could fit these better tyres to ICE vehicles, and then the tyres on the EVs would still wear out faster?
https://www.thisismoney.co.uk/money/cars/article-11835405/IMI-warns-MOT-delay-spark-rise-EVs-worn-tyres.html
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Jo Nova has a story on this topic here.
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Don’t forget that tyres are one of many essential products that are made from oil derivatives.
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Jit; fitting tyres designed for heavy EVs to normal cars would probably make the ride very harsh – although they might last well longer!
Robin; you make a good point – one which is under-appreciated in discussions of ending fossil fuels. One example is sulphur, a key chemical for a myriad of processes and applications. A very large part of the world’s supply comes, very cheaply, from processing crude oil and gas. If that supply is curtailed, we will have to revert to mining with obvious cost and environmental implications.
Aiui, 10 – 15% of oil and gas production is used as feedstock for a multitude of processes.
Those seeking to shutdown oil and gas should be challenged as to how all of the products derived from them would be replaced – affordably and at scale.
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Yes, Mike, they should be so challenged. The list is formidable: it includes concrete, steel, plastics, fertiliser, pharmaceuticals, anaesthetics, lubricants, paints, adhesives, tyres and asphalt – all essential to our lives and wellbeing and all of which either require the combustion of fossil fuels or are made from oil derivatives.
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WUWT on this topic: https://wattsupwiththat.com/2023/10/01/the-unseen-emissions-tire-dust-and-the-environmental-mirage-of-electric-vehicles/
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Kwikfit beg to differ:
“Tyre wear on electric vehicles
For a start, electric cars are much heavier than regular combustion engine vehicles due to the extra technology under the bonnet. Because of their increased weight, you would think that electric car tyres wear down quicker. But you’d be wrong.
If electric cars were fitted with the same tyres as ordinary vehicles, the rates of wear would be greater — but they aren’t. Electric car tyres are built to withstand the pressure of the increased battery weight and electric car. Manufacturers improved not only the rubber compound and sidewall strength but also the tread and groove design for resilience.
As a result, they are more expensive than regular tyres but due to their strain-absorbing structure, they will wear down less quickly. In fact, according to recent studies, conventional tyres actually wear down 30% quicker than their electric vehicle counterparts.”
Another counter-argument: EVs have far better torque control than ICE cars by virtue of their electric motors. That means less slippage = less wear. That may explain the comment above about ICEs using their tyres faster.
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Mike, the Kwikfit theory has a few holes in it. First, if there is a need for magic tyres, then they are implicitly admitting the tyre wear problem. Then it is an obvious point to make that we can simply install the magic tyres on ICE and the EVs are back to losing the tyre wear war again.
But there are no magic tyres. Tyre properties are the result of a number of compromises. One of the key ones is the trade-off of grip and wear resistance.
However, it is to easy to blame tyre wear on the excess weight. This is not automatic, and depends on the tyre footprint. But again there is a compromise between grip and increased rolling resistance, leading manufacturers (presumably) trying to reduce tyre footprints in order to max out range.
Acceleration inevitably leads to wear, whether it’s linear, or going around corners.
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Jit; I’m sure you know that tyres have been graded for load – and speed – for ages. I used to have a SEAT MPV which required a standard tyre size but they had to be rated for “extra load”. As you say, tyre design is always a compromise between grip, wear, ride, noise, wet/dry performance, and so on. EV-specific tyres are a different compromise.
Fitting “magic tyres” to a lighter ICE probably would give reduced wear but it would be at the expense of a harsher ride and maybe reduced grip.
It’s interesting that there has not been any outcry about wear/particulates/road damage for large SUVs which can often be very heavy (2.8 tonnes for the latest Range Rover!) and use aggressive tread patterns. It smells of searching for any stick with which to beat EVs.
I don’t have an EV, nor am I a great fan, but I do follow the debate with interest as I may well end up with one, sooner or later. Reading EV forums, fleet operators and many owners report very good tyre life although some of the VW cars seem to be worse than ICE.
There are many arguments against EVs, especially the compulsion now being applied by the ZEV mandate as well as the various tax incentives using our money. However the weight/tyre wear claims are weak, at best, imho.
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Mike, without a doubt an EV driver could drive their car in a manner that would cause its tyres to wear in a similar way to ICE. But if they drive like some of the EV owners around here, that will emphatically not be the case.
F = ma and thus if you want to accelerate the same mass at a faster rate, the force acting on the tyres (subject to the contact patch) will be higher. Ditto if you try to accelerate a heavier mass at the same rate. This applies whether going around corners, or accelerating from stationary. Thus an EV, as something typically heavier than the norm, and which has at least the potential to accelerate faster than the norm, has more potential for tyre wear. SUVs yes but mostly in cornering. But there are EV SUVs. (ESUVs?)
Of course when accelerating under power, then the acting force only applies to the driving wheels, so if you have an EV with 4 driven wheels you could be laughing.
My comment on the magic tyres was somewhat flippant, but what I was trying to get at is that if there is a compound that could increase grip and decrease wear, it would work just as well on ICE. Other physical properties of the tyres maybe would not work so well on ICE. There is still the caveat that the size of the contact patch is important, but if you increase it, you increase rolling resistance.
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Suddenly the Mail has noticed this story (as reported at the Daily Sceptic; I scanned the Mail’s news this morning, but it seemed to be full of Big Brother or some such tosh).
https://www.dailymail.co.uk/sciencetech/article-13156803/Electric-cars-release-toxic-emissions-petrol-powered-vehicles-worse-environment.html
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The Daily Sceptic link is here:
https://dailysceptic.org/2024/03/05/electric-cars-release-more-toxic-emissions-than-petrol-cars-study-finds/
It does little more than regurgitate the Daily Mail story, but at least it can be read without lots of annoying pop-ups and adverts.
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Jit: apologies…I missed your last comment on the tyre issue.
Afaik, the more powerful EVs are 4WD which eases the tyre loads under acceleration, as you say. Further, EVs have the advantage of far better torque control than conventional cars since electric motors allow near-instantaneous adjustments and fine control.
Reading EV forums, tyre wear seems to be generally better than for ICE cars. That might be down to the different tyre compound or – my suspicion – to EVs being driven relatively sedately. For all their vaunted acceleration, I have never encountered an EV being driven hard on the open road and it’s very rare to be overtaken by one on the motorway.
Intuitively I’d agree that a “magic” EV tyre compound should work just as well on an ICE of equivalent weight. Cynical old me wonders whether that’s what the tyre companies are doing but charging extra for “EV-specific” models.
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That article includes this comment: “It found that EVs are 30% heavier on average than petrol-powered vehicles, which causes the brakes and tyre treads to wear out faster than standard cars and releases tiny, often toxic particles into the atmosphere.”
Clearly the author doesn’t know the subject. It’s well-known that EVs have very little brake wear because retardation is normally provided by the motor(s) regenerating. Further, per the conversation with Jit above, tyre wear is generally better than for ICE, although the reasons are a bit obscure.
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This is an interesting – if highly technical – webinar by the boss of Emissions Analytics on tyre wear etc.
https://youtu.be/AR9iex4NdRs
According to him, EVs tyres wear faster but are less toxic – something to do with a higher proportion of natural rubber. (But overall larger tyres had better wear.)
The concerning thing for me was when he cited a study saying humans are passing some tyre-related chemical in their urine. It’s called 6PPD and I’m about to go an look it up to see how toxic it is!
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https://en.wikipedia.org/wiki/6PPD
Apparently it’s a sacrificial chemical that protects the tyre from cracking on reaction with ozone. The reacted chemical (a quinone) caused a die-off in coho salmon in California. According to Wiki, no-one knew it reacted to become a quinone until 2020. (Quinones I remember from browning of apples in A-level chemistry.) (Although why else would the tyre manufacturers add it, if not to react with ozone?)
(One of my favourite tasks in A-level organic chemistry was being given a diagram of a molecule and being asked to put a name to it. It was a puzzle but, following certain rules, you could obtain the correct answer. Alas, looking at the diagram of 6PPD, I had no idea what its name was: N1-(4-Methylpentan-2-yl)-N4-phenylbenzene-1,4-diamine.)
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