222 - The EV Tyre Episode

Gary C: Hi, I'm Gary and this is episode 222 of EV Musings, a podcast about renewables, electric vehicles and things that are interesting to electric vehicle owners. On the show today, we'll be looking at EV tyres and the myths and facts surrounding them. Before we start, I wanted to say thank you for anyone who gave feedback on last week's episode.

Hopefully, as you make your move into EV ownership or usership, it will make your life a little bit easier if you need to public charge. Now, our main topic of discussion today is tyres, specifically tyres for your electric vehicle. And I'm going to be looking at this from two points of view.

Firstly, I want to talk about the role that tyres play in the efficiency of your electric vehicle. And secondly, I'm going to be looking at the issue of tyre dust, a particular matter and whether running a heavier car will result in more emissions from tyres and indeed brakes than other types of transport. Now, you may have heard me talk in the past about the time before EVs when I drove a certain German rear engine sports car.

I had three different models over 10 years and I loved them. My standard joke at the time was that they passed everything except the petrol station. I later modified that to be they passed everything except the petrol station and the tyre place.

I was forever getting punctures. The amount of money I spent on tyres was ridiculous. I recall getting two punctures in four days at one point.

Now, there is an electric Porsche driver on social media who seems to think that punctures occurring with their car are EV related. And I can tell them from experience that it's the fact that their car has wide, low profile tyres and it's nothing to do with the fact that it's electric. Now, on top of that, getting back to my German sports car, I was replacing sets of tyres fairly regularly.

And this was due to a number of reasons. The primary one was that these were low profile wide tyres that had a lot of grip in the dry and had to deal with a lot of power and they wore down relatively quickly. And the second reason was that I kind of liked putting the foot down in the car and the wheels were very easy to spin.

Now, in hindsight, that probably wasn't very intelligent. I was only making my own life harder by burning through rubber at a higher rate of knots than I needed to. There was the expense and inconvenience.

Two takeaways from this were that this particular car brand was susceptible to punctures and that your driving style has a large influence on the tyre wear. Now, once I got rid of that car, well, actually, I wrote it off in an aquaplaning accident. As I say, this car was great in the dry, less so in the wet.

I then moved on to an old faithful Honda Civic. Totally different car, totally different driving characteristics and totally different tyre wear. It was far less powerful and it had narrower, more high profile tyres, which lasted much longer and had fewer punctures.

Now, the weight difference between these two cars was 96kg. Now, with these two bits of anecdotal evidence, would you say that the different tyre wear was a result of the vehicle itself, the driver, the tyre, or a combination of all of them? Have a think about that while we continue our discussion on tyres.

The Little Book of EV Myths, link in the show notes, which was produced by Stop Burning Stuff, talks about tyre wear. I want to quote this segment because it brings up two specific bits of information. All tyres wear and leave nanoparticles in the atmosphere and particulates on the ground.

In: 2021

The CEO of the ProHyre Group in the UK said, simply, quote, the tyre wear is the same as the equivalent diesel, end quote. We definitely do have a tyre particulate problem from all vehicles and scientific research is needed to properly establish EV tyre particulate pollution, end quote. We'll talk with Dr McTurk a little later about his involvement in this report.

But let's start talking about tyres themselves. So what role do tyres play? Now we've talked before in the show about the ways you can make your car more efficient.

A more efficient car moves through the air better than a less efficient one and this in turn improves the range and reduces charging stops. Now there are many things that play into efficiency but one of them is your tyres. They are the only thing that's in contact with the actual road and as such provide one major source of inefficiency.

To put it bluntly, poorly designed tyres will waste energy and cost you money. And it all comes down to what's called rolling resistance and this is a measure of how much friction the tyre imparts on the road. Now as a general rule of thumb, tyres need friction.

It's the friction that provides the grip and the grip that keeps the car on the road rather than sliding off into the ditch. As anyone who's hit a piece of black ice on a wintry morning will attest. Now if you want the scientific definition, rolling resistance is actually the force resisting the motion when a body such as a ball, tyre or wheel rolls on a surface.

It's mainly caused by non-elastic effects, that is not all the energy needed for deformation of the wheel is recovered when the pressure is removed. So now you know. Basically in a tyre there's a phenomenon known as hysteresis.

As the tyre rotates under the weight of the vehicle it experiences repeated cycles of deformation and recovery and it dissipates the hysteresis energy loss as heat. Now as we all know from basic physics classes, energy can neither be created nor destroyed, merely transferred. In this case the energy to move the car forward is transferred into heat from hysteresis.

This is effectively lost energy from your vehicle's battery and if energy is lost from the battery that doesn't go towards propelling the vehicle forward and that will reduce your range. My German high-end sports car that I drove for 10 years had massive tyres, low profile so they didn't stand too proud from the rim but very very wide and this provided a lot of rubber in contact with the road. For hooning around country roads in the depths of Hampshire they provided lots and lots of traction and grip until of course I hit a river of running water streaming across the road at which point they turned into buoyancy aids, lost all grip and aquaplaned me right into a telegraph pole.

But that's another story. But for providing efficient driving with minimal rolling resistance they were not good. No doubt with slightly narrower wheels or indeed a higher profile one I might have managed to get more than the 28 miles per gallon that I was averaging with them.

Which brings us to EV tyres. Now many brands provide tyres which are marked as low rolling resistance. They usually have the word eco or some reference to e in there somewhere.

Examples of low rolling resistance tyres are Continental EcoContact, Goodyear Efficient Grip, Mischler e-Primacy. Other makesound types are available. If you want to be as efficient as you can with your electric vehicle, make sure you use a good tyre specifically designed for electric vehicles with low rolling resistance and make sure the tyre pressures on your car are kept at manufacturer's prescribed level.

This reduces hysteresis, increases efficiency and adds miles to your vehicle range. This is especially important in winter or general bad weather where anything on the road such as snow or standing water will also increase your rolling resistance. We'll come back to this in a short while, but I now want to talk about the issue of tyre dust.

One piece of FUD, fear, uncertainty and doubt that seems to have taken hold in the popular media is the one related to EVs providing higher or producing higher levels of tyre particulates. It seems that someone linked heavier EV weight to increased tyre wear. At first glance, this would appear to make some sort of logical sense.

Gary C: But that's not actually the case. So what's got Ewan in such a tizzy?

Euan: There's a particular report from Emissions Analytics that some of the tabloids love to run.

and it did the rounds back in: 2022

There's like a thousand times more particulates that come off the tyres than there is that comes out of the exhaust of a big pickup truck or something like this. That's not the truth at all. So there was a study and then there was a press release.

The press release is the one that has done the damage because it didn't specify the conditions of the study. So what they did was they took a petrol car, I believe it was. It was certainly not electric, it was a Volkswagen Golf.

They drove it and they measured the rate at which the particulates were coming off of the tyres and they concluded that it was like a thousand times more than the particulates that you get out of the exhaust. What the press release didn't mention that the actual study did was that in order to measure the tyre wear, they thought, hang on a minute, if we drive this regularly it's going to take so long to achieve any sort of significant degradation and particulate production by the tyres. So what we'll do is we'll load up the thing with success ballast like a touring car and then hood it around a racetrack and then see what the results are.

And I have the results that were mentioned in the press release in front of me. They claimed that it was 9. 3 grams of particulate matter that would come off of those tyres per mile.

So a gram, you can imagine what that feels like in your hands. You're starting to get to a tangible amount of rubber that's coming off of these tyres. But the thing is, your typical 16 inch rim family car tyre is about nine kilograms.

So if you have four of those, that's 36 kilograms, you divide that through by 9. 3 grams per mile and you find that that is implying that those tyres, all four of them, physically disappear. And I'm not just talking about the tread having to come in for a pit stop, you know, we're talking running on the rims, skating along on metal or hubcaps in less than 4,000 miles.

Bearing in mind that the average UK motorist does about 8,000 miles a year. So that's obviously a load of bunkum. Now that report, co-authored by Nick Holden from Emissions Analytics, has quite rightly been debunked, but he's still quite happy to let it be quoted on social media posts to this day.

Now, although he did try to rectify the issue a little more recently, though. To be fair, yeah, I believe there's been a follow-up article where they've tried to do kind of damage limitation. Well, I say damage limitation, it's worked out very well for them.

And I think that maybe the figures are slightly more believable, but they are still inaccurate. And part of the reason is, such as the way they've done this test, it seems like they've not actually taken into account any particulates that were already on the road that are being kicked up by the tires of the electric vehicle that they've tested, or any vehicle that they've tested for that matter. And that's an issue because there are quite a lot of particulates that lie on the road as it is today.

Because funnily enough, there's tire particulates from other vehicles. There's general fine particles from brake pads, and that includes everything from bikes all the way up to double-decker buses. There's even exhaust pollution as well, which, by the way, those particulates you get in exhaust pollution love to concentrate themselves at child and pet height, and they are not nice to breathe in.

They cause cardiological issues, let alone respiratory. They are nasty particulates and you do not want those in your system. So it's the equivalent of me going Gardalo and then chucking a whole bunch of sewage onto the road and you accidentally wandering through it, absentmindedly, without checking.

And then me going, oh, look at all that sewage on your shoes. It's like, no, no, no. That was not your fault.

You just kicked up what was already there. And of course there's going to be wear and tear from electric vehicle tires, but it's important that these studies actually determine how much of those particulates came from the vehicle that they are measuring it from. And that's where it's important to weigh the tires before and after and so on.

And to be honest, from what I've seen of that study, I am not entirely convinced that it was done to the sort of standard that I would find believable.

Gary C: So what is the truth when it comes to tire particulates? Well there was a more recent study published in book form called, Non-exhaust particulate emissions from road transport colon, an ignored environmental policy challenge.

It's a thrilling sounding title, I'm sure you'll agree. But in it, there was a segment on the implication of electric vehicle uptake for non-exhaust emissions.

Euan: It was quite a pragmatic study.

They looked into lighter weight EVs that would have a range of 100 miles or less, urban mobility basically. And they found that non-exhaust emissions were reduced by between 11 and 13% for PM2. 5, that's your really fine nanoparticulates, and almost 20% less for PM10.

If you start to look at battery packs or vehicles with battery packs that enable a range of 300 miles or more, you're starting to look at bigger, heavier vehicles, probably heading towards SUVs, which are inherently bigger and more material intensive and therefore heavier anyway. You find that they only reduce PM10 by four to 7%, but they actually increase PM2. 5, the super fine stuff, by between three and 8% relative to petrol or diesel cars.

That's an interesting comparison, and I think that that is fair. However, you then add in the exhaust emissions and the EV wins hands down. That's the important take-home message.

Mason So let's talk a little bit about tyre price and tyre durability. Euan, are cheaper tyres worse when it comes to EVs? Ewan I personally do not have data on that, but I can tell you that if you buy cheap, you buy twice.

And I said, I don't have data in terms of peer-reviewed scientific studies, but I do have…and this is something that emissions analytics don't like…anecdotal evidence. But that anecdotal evidence comes from genuine fleets, and those fleets are ones that run electric vehicles. They don't just load a Volkswagen Golf with ballast and run it around a test track at high speed.

Well, actually, they do something similar to that because they are private hire… car drivers and they drive their cars like they stole them, because they've got places to be, customers to pick up and fares to collect. There's some taxi companies that I've spoken to in Dundee, for example. I say taxi, private hire.

I don't want to get those two mixed up. Anyway, the point is, it's a bitter rivalry. The point is, there are these companies who are running fleets of electric vehicles where the drivers do have a heavy throttle foot.

They tend to fit cheap tires and they tend to find that the lifespan is maybe nearer to 15,000 to 20,000 miles. But you compare that to pretty much the same make and model of vehicle being used as a very high mileage cross-country service vehicle. So if we look at Cleveley EV Mobile and the MG5, which of course has now got to the same stage as the Skoda Octavia.

If you're driving through a busy city centre on a Saturday night and you own an MG5 or a Skoda Octavia, you will have some drunk person chop on your windscreen and go, it is back home, because everyone thinks that they are taxis or private hire cars. That's because they're reliable. Always go for the cars that private hire drivers go for, because they tend to be the reliable ones.

The point is, anecdote aside, that these private hire companies are getting 15,000 to 20,000 miles out of the tires. The latest update I have in front of me from Cleveley EV Mobile is from their two-year and seven-month-old MG5, which has now clocked up 133,514 miles. The battery, by the way, is still over 90% state of health.

It got its first set of replacement tires at 51,000 miles. It then needed them changed again at 101,000 miles. So they managed 1,000 miles less on their second set, but the good news is that both of them still did at least 50,000 miles before they needed changed, which is more than twice what the private hire drivers were managing.

The third set is looking so-so. At the moment, it probably will need to be replaced within 45,000 miles. The price of those tires, by the way, for all four of them, was 280 quid a set.

We're not talking horrifically expensive tires here. We're just talking get a half-decent make, a reputable make. As long as you don't have too heavy a throttle foot, you will be able to extend the lifespan of these tires.

In fact, between us, we know EV drivers who said that the lifespan of the tires they're getting out of their electric vehicles is greater than the lifespan of the tires of the petrol or diesel car that their electric car has replaced.

Gary C: Now, we talked earlier about a report you did for the RAC on tires. Talk to me a little bit about that.

Euan: So the RAC were similarly fed up with all of this disinformation that was doing the rounds. Particularly, a thousand times more particulates come off of a tire than out of a lovely, clean exhaust pipe. Have fun running a hose from an exhaust pipe through your driver's window.

See how long it is before you burst out the door coughing and spluttering and going, that wasn't very nice. That's particulates for you. So we decided to sit down and pragmatically respond to this.

I looked into the studies that were causing this kind of disinformation to spread and quickly spotted the holes in the data, or the way that it was presented, or the way that it was interpreted by tabloids and so on. I then reached out to fleets, not least Cleveland EV Mobile, British Gas, as I mentioned the taxi company in Dundee, or its private hire company in Dundee. I was asking them, what sort of range are you getting out of these tires before you need to replace them?

The results were somewhat varied, but generally speaking, if it was driven harshly and it was cheap quality tires, you didn't get a very good lifespan. But guess what? The same applies to a petrol or a diesel car.

Whereas if you drive, not even like driving Miss Daisy, just drive normally an electric car, so sensibly, and fit a decent set of tires, then I suppose it's like buying a new pair of shoes. If you buy a more expensive, without necessarily being like a designer brand pair of shoes or anything, chances are that is going to last a lot longer than a really cheap pair of shoes. It's the exact same for the rubber that goes on the wheels of your car, as it is on the soles of your feet.

This is what this article has concluded. We also looked into other sources of emissions, not least brakes. Brakes are something that can emphatically have their emissions reduced by an electric car.

Because with a petrol or diesel car, you don't have regenerative braking. You are heavily dependent on the mechanical foot brake to slow the car coming up to a stop. As a result, you end up spewing quite a lot of fine particulates into the atmosphere, or into, I should say, child and pet height within urban areas, which is not good.

If you have an electric car, you can use regenerative braking, and that regenerative braking obviously helps to slow down the car using the electric motor. You barely use the foot brake, to the point that some brake pads and discs need to be refurbished or even replaced because they've rusted up, because nobody's used them. There's actually a bell curve with brake pads and discs on electric cars.

You need to give them a good stab at some point or another. Drive to an industrial estate, take it up to speed, make sure there's nothing behind you, slam on the brakes and condition them, basically. Burnish them, I believe is the technical term.

That's what I'm looking for. So you kind of burnish the brakes and – yeah, yeah, there we go. I sound like a proper mechanic now.

Yeah, you just want to burnish the brakes, mate. Keep them in good neck. That's what you do to keep an EV's brake pads and discs in excellent shape.

Your typical petrol or diesel car has a brake pad disc lifespan of about 40,000 miles. I was going to say per charge, I'm so used to dealing with EVs. But 40,000 mile lifespan for the brake pads.

In an EV, you can be looking at easily in excess of 100,000. That's something that was found amongst all the fleets that I chatted with for the RAC article. It's certainly something that is found with most EV drivers.

I can speak from lived experience of my very old school Tesla Model S, which has done very similar mileage to James's MG5 from Clevely EV Mobile. So it's up there in the mid-130s. I quite recently had to replace all the pads and discs, but it was because they'd actually warped rather than worn.

They were just that old. So, you know, replace them, take them out on a back road and burnish them. You know, you want to do that.

You want to burnish them and bring them in. And yeah, they're great. So anyway, long story short is that you're looking at two and a half times the lifespan of brake pads for an electric vehicle versus a petrol or diesel.

Gary C: Now, the question that arose in my mind after listening to Dr. McTurk was this, what happens to the particles that come off the tyre? Which led me to a company called the Tyre Collective, who have a rather unique solution for this.

Hanson C: So I'm Hanson Chang. I'm one of the co-founders of the Tyre Collective.

Gary C: We'll get onto or into what the Tyre Collective do in a second.

But first, I want to understand what the scale of the problem is. Are there stats for tyre wear and particulate matter?

Hanson C: The UK Department of Transport, the air quality expert group, has shown that I think up to 73% of PM10 and PM2.5 of non-exhaust emissions, which is tyre wear, brake wear and road wear, end up in the air. As a way of illustrating this, the Tyre Collective website has a great little graphic showing transparent cubes of various sizes filled with tyre particulates. There's a car, a single bus journey and a whole day's bus journey on a couple of routes.

Those are estimates based off of literature reviews. What we did was track various TFL bus routes and kind of average driving routes and multiplied those. We thought it was important to visualize how much particulates or how much kind of mass of rubber we're talking about, It's this kind of invisible pollutant that a lot of people can actually see.

Gary C: So let's talk a little bit about what the Tire Collective does.

Hanson C: So at the Tire Collective, what we focus on is build solutions to actually capture tire wear. So we found that the tires themselves, as they're produced, are charged from friction with the road.

So we're able to use electrostatics to attract and capture it. So we developed this box that sits kind of behind the wheel. So as you're driving, the particles are produced, it gets picked up in the airflow behind the tire and goes through our device and a series of electrostatic plates attract and capture.

We also focus on how we can, we also look at kind of the whole cycle of tire wear as a pollution. And once we capture it, how do we kind of upcycle it to ensure kind of a closed-loop system to make sure these particles are not going to the landfill. And we also work with researchers around the world to kind of fill knowledge gaps on tire wear because it's a relatively new area of research.

And then what we have are some of the first on-road samples of tire particulates.

Gary C: The device itself, it looks a little like a box. It sits below the bodywork and directly behind the tire.

The model and the photo that's there on the website, as of the time of writing, is an earlier prototype and it doesn't actually reflect the current version. I asked about airflow and efficiency and whether there will be a hit, but Hanson told me that this area is airflow turbulent anyway, so there's going to be a minimal impact in terms of the efficiency. The device is linked into the vehicle's 12-volt system and it draws power from there to run the electrostatics.

Now, I want you to loop back to what Hanson was saying about recycling.

Hanson C: Yeah, so the particulates themselves are a form of micronized rubber and that's actually a very established industry. At the moment, a lot of that feedstock comes from end-of-life tires that have been ground down, but what we're replacing is this kind of very fine micronized rubber that we can use in new tire production.

You can use them in shoe soles. We've made batteries out of them in the past, so there's a lot of different avenues that we're exploring with this material, this pollution now as a material.

Gary C: I think that's pretty cool, the way they're using the particulate matter to actually make brand new tires.

It's a bit of a win-win, right? Now, Hanson also told me they're about a year away from commercializing this product, and the target market at the moment is three and a half ton vans doing things like last mile deliveries. The unit itself is aimed to be priced around £150 per device and you would fit either two or four per vehicle depending on your needs.

Ideally four, right? So, £600 per vehicle. In the big scheme of things for fleets, that's not a huge hit.

The electrostatic plates themselves, they're almost like an air filter and will need cleaning every so often to remove the particulates that build up. The hope is that this will be included in the regular servicing of the vehicles. Now, Hanson told me that this would take between two and five minutes per vehicle.

The plates are reusable and they just need emptying as part of the service. A couple of takeaways from this then. Firstly, the stories that EVs produce more tyre particulates is flat out incorrect and based on inaccurate data and testing.

Tyres are lasting as long as and even longer than the tyres on similar non-electric cars. Fleets across the country have confirmed this from their underlying maintenance data. Also, the other aspect of emissions that EVs beat ICE cars on hands down is brake dust.

You're more likely to need your brakes replacing due to them seizing up through the lack of use than you are to need them replacing because they're worn down. This naturally reduces emissions from brake dust, which is a big contributor to PM2. 5 particulate matter pollution.

Finally, there are novel methods for capturing some of the tyre particulates that are emitted on either EV or ICE cars and using that to produce something more useful than poor health outcomes in children. Who would have guessed? This season we're looking at raising the awareness of carbon literacy with our listeners and one way we're doing that is with a carbon fact as read by carbon literacy trainer, Anne's Nelson.

Anne : Did you know two-thirds of all cereals grown in the EU are for animal feed? So that's another reason for reducing your meat and dairy intake because fewer animals means more food for everyone.

Gary C: It's time for a cool EV or renewable thing to share with you listeners.

Fully charged viewers may have seen this on a recent episode but I was rather taken by a portable wind turbine that Robert Llewellyn and Imogen Bogle demonstrated. Wind turbines are ideal complements to solar panels because in most places wind and sun are complementary, i. e.

when one is active the other tends not to be. So having a wind turbine you can erect in your backyard or wherever you can pop out for a while is an ideal way of getting power. Kitex is a company creating these portable turbines.

They can be erected fairly easily in your back garden. They weigh around 12 kilos and they can output 200 watts with a 50 mile an hour wind. Now that may not seem a lot but that sort of wind over 24 hours would produce about four and a half kilowatt hours and that's enough to do quite a lot of stuff around the house.

Now you're not going to be able to run your house off one of these and indeed Kite don't recommend you do that at all but if you couple this with the storage battery such as a Jackery or an Ecoflow you can use that to store the generated power and also to dispense that generated power via a three pin plug or a USB charger. I love this I think it's a great idea and I'll link the fully charged video and the Kitex website in the show notes. I hope you enjoyed listening to today's show.

It was put together this week with the help of Dr Ewan McTurk and Hanson Chun from the Tire Collective. Many thanks for their time and expertise. I've always enjoyed having you on the show as it's a font of knowledge when it comes to things like this and we'll hear more from the good doctor later in the season.

If you have any thoughts, comments, criticisms or other general messages to pass on to me I can be reached at info at efemusings. com. On the socials I'm on Twitter or ex at musingsev.

I'm also on Instagram at evmusings where I post short videos and podcast extracts regularly. Why not follow me there? Thanks to everyone who supports me through Patreon on a monthly basis and through Ko-fi.

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Check out the links in the show notes for more information as well as a link to my regular EV Musings newsletter and associated articles. Now I know you're probably driving or walking or jogging right now as you listen but if you can remember and you enjoyed this episode, drop me a review in iTunes please. It really helps me out.

If you've reached this part of the podcast and are still listening, thank you. Why not let me know you've got to this point by tweeting me at musingsev with the words Feeling very tired now. Hashtag if you know you know, nothing else.

Thanks as always to my co-founder Simone. You know he's becoming a bit of a classic car enthusiast now. Despite his love for electric, he still thinks we should keep the old Cortinas, E-Type Jags and classic Aston Martins.

He loves to go and visit shows on a weekend. The only problem is he gets a little too involved with the owners. So much so that they end up handing him a cloth and getting him to help with the maintenance.

Euan: Yeah, he's just wanted to abolish the brakes, mate. Keep them in good neck.

Gary C: Thanks for listening.

Bye.