> "Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles."
It does not seem to be a mistake:
> "Compared with regulated exhaust emission limits of 4.5 milligrams per kilometer, the completely unregulated tyre wear emission is higher by a factor of over 1,000."
A tire might way up to 15 kilograms for a 20 inch type. Lets assume 10 kilograms for a normal tire which is on the high side. 4 tires is 40 kilograms. Even if we assume half of the particals are not coming from the tire (but from where?). That still leaves 40,000 / 2.9 = 13793 kilometers for the tires to be completly consumed (weighing nothing anymore). That is definitely not happening.
So without an explanation on where the matter is coming from this does not read right.
They're torn up from the road and rubbed off from the tyres themselves. The majority is obviously coming from the road.
There's been studies done here in Sweden since we've banned studded winter tyres in some areas of Stockholm in an effort to reduce road wear and improve air quality. I don't know of any sources in English off the top of my head though.
The last time I read an article about it though (2+ years ago, during Diesel-gate), the findings was that the danger in the particles comes from their size with smaller particles being more dangerous for humans. And that road particles were something like an order of magnitude larger than exhaust fume particles from diesel engines.
We've since banned diesel engines inside Stockholm as well so the whole thing is moot here.
>They're torn up from the road and rubbed off from the tyres themselves. The majority is obviously coming from the road.
Not sure even that adds up to believable.
The Sydney Harbour Bridge is about 500m long between the pylons. It has "more than 150,000 cars per day" on it (according to the snippet from a google search). If all of that was from the road, that'd mean there's about 160 tons of road getting torn up per year. It looks to be ~30m wide on Google Sat view, and "google first hit" research indicates road base weighs 1.9tons per cubic meter. It's be losing almost 6cm of depth along the whole span every year if all those numbers hold, or 3cm per year if "only half" of that comes from the road and the rest from the tires. They don't resurface it anything like often enough for that to be true...
Let's test it with basic math! The claim is "...performed some initial tyre wear testing. Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles.
If the average tire lasts 40,000 Kilometers then multiply that by 5.8 grams = 232Kg. 232Kg/4 tire per car = 58Kg per tire of tread. The tread is about 35% of the tire so the tire would need to weigh 165Kg. The average tire weights 20-22Kg, so that's a damn big tire!
New Asphalt might get tour up and account for additional particulate matter, but my understanding is that process slows considerably once the aggregate (small rocks) is exposed.
But is it a long stretch from the claim: "Non-exhaust emissions (NEE) are particles released into the air from brake wear, tyre wear, road surface wear and resuspension of road dust during on-road vehicle usage."
Resuspension of road dust is literally one of the 4 things they defined as the NEE they're measuring.
But counting "resuspended road dust" as "emissions" seems pretty far fetched to me. Especially if that's a significant portion of the "5.8 grams per kilometer of particles", and you then push out a press release with the hyperbolic headline claim "Pollution from tire wear 1000 times worse than exhaust emissions."
And they then have the audacity to claim: "Emissions Analytics seeks to bring transparency to a confused market sector."
Pretty sure I know who's funding them now, without even bothering to google it...
That doesn't make sense to me either. Take a busy German highway (as I don't know the average load on US ones), easily 100k cars per day. There are parts of highways which don't get replaced for 20 years easily. Plus apart from tiny fraction of north europe (and maybe Canada?), nobody ever uses studs.
Back of the envelope math tells me 1 km of highway would lose some 730 tonnes of asphalt, per year (so 14,600 tonnes in 20 years). If we talk about normal car wear, this simply isn't happening on those unkempt roads. It would leave huge lanes of deeper surface where asphalt is lacking. There isn't visible wear on lanes that are used mostly by cars like that. Roads have mostly potholes.
What happens on those roads is, sticky asphalt is worn away (but not at the mentioned rate), and what remains are stones which basically don't wear, and tires touch only that. At least highway surface I saw was like that.
What damages roads greatly are trucks, especially overloaded ones (say limit is 15 tonnes, they take 22 tonnes and hope to not be checked... welcome to east european mentality).
Indeed, trucks greatly damage roads. For example a 2 tonnes car has 2 axles, hence a=1 tonne per axle. A 20 tonnes truck with 2 axles has b=10 tonnes per axle. Then, the road damage per axle increases by a power of four [1], i.e., by (b/a)^4=10000.
> "the danger in the particles comes from their size with smaller particles being more dangerous for humans. And that road particles were something like an order of magnitude larger than exhaust fume particles from diesel engines."
Exactly. It might look bad when you compare the mass of particles, but if you compare the particle counts, it's exhaust emissions that produce the big numbers - of really tiny (sub-PM2.5) particles.
The studs in tyres are small carbide rods, which will easily chew through a soft material like asphalt. A rubber tyre would seem to be quite a bit softer than asphalt in colder conditions, so I have a hard time imagining the rubber wearing the asphalt down so significantly.
Study mentions EU and source company has offices in Stokenchurch, UK and Stuttgart, Germany. I doubt they tested with studded tires and called it typical.
They did test with brand new tires - that's the likely source.
"Emissions Analytics .. [self proclaimed?] leading independent .. specialist for .. measurement of realworld emissions .. performed .. initial tyre wear testing. .. on brand new, correctly inflated tyres .. [and] found that the car emitted 5.8 grams per kilometer of particles."
I have been wearing studded slip on crampons when walking my dog this winter. The ice has been ridiculous, I’ve fallen twice already when not wearing them. Not great for the sidewalks, I know, but the dog needs his walks or he would... get sad
Weight of a masonry hammer is nothing compared to the weight of a human, yet it can destroy concrete with ease.
I'd guess it depends on how and how much you walk on what kind of pavement with what kind of studded shoes. Damage can realistically be imperceptible or ugly.
Concrete sidewalks are pretty fragile. Unless they're freshly laid, most that I see have cracks and pits to some extent (probably mostly attributable to cooling/heating and water). Some people also seriously drop their feet down hard when they walk, and if they've got little bits of metal sticking out from the bottom of their shoes, I imagine that damage adds up and doubly so if it slams down an existing crack.
I know you are joking but just to answer the question anyway, if the tires are completely flat then they are not supporting the car and you can't use them for measurement.
If the tires are partially flat then they are supporting the car and the PSI is correct and you'll notice the tire spreads out wider on the road so the ground force is lower because it's spread out over a larger area.
Technically you have to also include the springiness of the sidewall in the measurement not just the PSI of the air.
>>if the tires are completely flat then they are not supporting the car and you can't use them for measurement.
Run-flat tires are a thing though - you can drive on them even with no internal pressure, there can be a gaping hole in it and you can still drive on them. So what's the pressure the car exerts on the road when driving then?
I can understand the car part (pounds per square inch) but why would a person's feet have more than 35 psi? If I have something like 60 (30 per) square inches of feet, and I weigh 180lbs, would that be 3 psi for my feet? Even if only parts of my feet were striking the ground at a time, how would that be more than a car?
Yeah, but there's a lot of water, and it can run over concrete for hours if not days at a time - of course it has an impact simply due to the sheer volume of it. Again, how does it compare to the miniscule impact of studded shoes?
If the particles were coming from the road then roads would wear in very visible ways.
But we don't actually see that kind of wear. Roads don't typically have grooves on them where the cars go that are lower than the middle which doesn't have tires driving over it.
Some discussion down-thread about this also, somebody runs the numbers for the road itself.
If the emissions numbers are right, it can't be matter that is being consumed or discarded, so it has to be matter that is being returned to the system and "emitted" again. Crap on the road itself meets this requirement -- a car drives by, throws up a bit of rubber off the tires, a bit of asphalt off the road, and a lot of junk from the road surface, and almost all of this stuff falls back on to the road to be thrown up again by the next car.
The article doesn't say how the measurements were done, so it's possible they sampled a small fraction of the air and measured the density, so having the junk available to the sensor doesn't necessarily rule out the recirculation idea.
But if the junk is mostly recirculating, then maybe the health threat is not as bad as if it's being emitted off the road and being lofted into the air with a long dwell-time?
Lots of things are possible and consistent with what the article states, evidently more research is needed.
Rubber has a density of 1500 kg/m^3, a tyre wears about 5mm before it needs to be replaced. If I say a tyre has a radius of about 0.3 metres and a width of about 0.2 metres and plug this into the equation for an annular cylinder I get about 2kg of material lost between new and needs to be replaced per tyre. I don't know how long tyres last for most people, but I would guess about 50000km. So I would expect about 0.2 grams per km from tyres...
I did the calculation in Freedom Units and converted to grams per km. Assuming tires last 60,000 miles or 100,000km and got 0.1 gm/km. So matches your analysis closely.
Notable I put 60,000 miles on my cars tires since I bought it. They are due for replacement kind of whenever.
Excellent use of back of the envelope math. I wonder if maybe the loss is non-linear, and a bit more is coming off because the tires are brand new. Perhaps there’s some coating on new tires before they ‘break in’?
Perhaps, but that would have to be a pretty steep curve, and one would expect that kind of falloff to have shown up in the data here (unless they literally drove the car once for only 1km, which...would be its own problem for credibility).
"Non-exhaust emissions (NEE) are particles released into the air from brake wear, tyre wear, road surface wear and resuspension of road dust during on-road vehicle usage."
Roads are filthy. Cody's Lab once did a video where he collected road dust from the side of a highway, and refined out all the precious metals from it. That's from one small section of highway, just imagine the scale of the pollution across the whole of the states. Concrete dust, rubber, metals, fuel, oil. Cars and car infrastructure is dirty business.
If one are outside near any mountainous road here in Northern California, motor vehicles pass by with the odor of brake pad + brake disc (mostly brake pad?) near the bottom with a very strong, distinctive bitter sweet metallic odor and that's probably a tiny proportion of the material.
Not sure if this test was set up to measure this, but brake dust, which contains all sorts of noxious particles, is a huge component of automobile emissions. This probably doesn't answer your question, however, because brake pads themselves only weigh so much...
A study linked last time this came up on HN indicated most of the particulate pollution is "resuspension", or previously generated particles kicked up by the car passing. It makes sense to consider in some cases but I think it's misleading to quote those numbers in some contexts, leading to confusion like this.
I would guess the measurement is more like how much dirt and dust is involved with a car driving driving down the road. Like brake dust, tire stuff.. and then that stuff being kicked up from the road surface by other cars and so on.
And yes it's super filthy and gross. I live on a busy street (but not a main street, so not THAT busy)... and my bathroom windowsills turn black after about a month because of brake dust and other car grossness.
Could there be an alternate way to measure the rubber wear off from vehicles? By considering the average distance after which a particular Sedan/SUV/Hatchback needs to change tyre, and then comparing the lost weights of old tyres and averaging that?
I'm just wondering if there are any alternate ways to correctly measure this emission.
I agree. But tires do shed a lot. Consider a brand new tire has grove depth of about 8-10mm, and many drivers change tires when their groves are 0-2mm (yes, some idiots keep driving until they have slicks or "a pop").
Turns out you don’t need to measure air pollutants, you can just divide lost rubber by the distance travelled. It won’t be anywhere close to what was measured, but then again actual particles are a much more useful number because you can’t breathe a worn down groove.
> Take a 40t truck with 5 axles vs. a small car with a weight of 1t and two axles ...
Truck driver. Not quibbling, just adding nuance.
For your typical 40t scenario, allowed max weights are:
12,00 pounds on the front steering axle. It has one tire at each end.
34,000 pounds total on the two tandem "drive" axles on the truck. There are two tires at the end of each axle, so four per axle, eight total at the drive axles, and ten total on the truck.
34,000 pounds on the two tandem axles on the trailer, two tires at the end of each axle, eight total on the trailer axles, 18 total on the truck plus trailer rig.
34K + 34K + 12K = 80,000 pounds = 40t, if the trailer is fully loaded to max. It's about 35,000 pounds total if the trailer is empty.
So you should include in your calculations that the load is spread out over eighteen tires, as above.
True, reducing the cargo would require more trucks to carry the same load, increasing demand for truck drivers.
On the other hand, wouldn’t reducing the amount of cargo a single truck can carry makey individual truck driver less valuable?
The end result would probably depend on a lot of other factors, including the supply and demand curves for alternative forms of transportation (trains, boats, investment in autonomous solutions), as well as the supply and demand curves of the goods being transported (because if the cost goes up to pay for more truck drivers, maybe people will just stop buying that product).
Or for the companies who will own/lease the automated fleets, foregoing having to pay wages, health insurance, vacation time, or work breaks allowing them to ship quicker since they aren't forced to stop driving and take a break every x hours. You'll just get a smug smile and a "learn to code" line.
No, for the roads it would be better to have the weight distributed on more "area", hence: more wheels and bigger wheels for the same weight. And this does _not_ require more trucks, just more wheels below each truck.
However, an even more material-efficient solution would be to use railways instead.
> Truck driver. Not quibbling, just adding nuance.
You're absolutely quibbling though.
> So you should include in your calculations that the load is spread out over eighteen tires, as above.
The fourth power rule is specifically about axle load, not about wheel load. It's also an estimate / rule of thumb (which is why it's so useful), not a precision instrument.
That's been the benefit to me, still having a drivable rig when a tire shreds.
But, there is also something called a "super single" that's a double wide single wheel/tire, with one on the end of an axle rather than two. I'm told they're cheaper and lighter total, as opposed to the more common two per end. I've pulled a few trailers that had them. I don't really know why one or the other, I just drive them.
It probably reduces wear slightly. Increasing contact area necessarily decreases applied pressure. Then again, a wider effective contact profile damages more of the road than a narrower one would.
Let's not forget the context of this discussion, however. Fourth power expressions are still fourth power expressions after multiplication by a constant factor. 4/18 is a constant factor.
You're multiplying the input by a constant factor. If wear is proportional to (weight per tire)^4, and you've halved weight per tire by having twice as many, you've just reduced wear to 6% of its original value.
I don't know if doubling tire counts really does this, but it's hard to see why twice as many axles would help but tires per axle would not. It's possible (the pressure underneath the tires is reduced, but the tires exerting pressure on the road are closer together) but counter intuitive to say the least.
And there's no proof in this thread that it doesn't help except for masklinn's misinterpretation of the original study.
"The AASHTO load-equivalency factors strictly apply only to axles supported
at each end by dual tires. Recent increase in steering-axle loadings and more
extensive use of single tires on load-bearing axles have precipitated efforts to
examine the effect on pavement wear of substituting single for dual tires."
Obviously you would try to saturate such tax revenues at the actual cost of road maintenance, so you wouldn’t actually collect $4000/truck mile, but yes, that’s the approximate ratio the taxes should be relative to each other.
If everyone switches to bikes, then weathering will be the primary form of road wear. It might already be so in harsh climates with freezing wet winters and hot desert summers (not sure though).
When built properly, roads are quite resistant to the elements, though the execution is often culture-dependent. Roads for light loads can be built much cheaper.
Snow plowing absolutely destroys roads. The blade catches on the smallest imperfections and creates potholes. Then water gets in and the freeze/thaw expansion cycle quickly makes things worse. Here in Canada roads really don't last very long before they have to be peeled up and put down again.
Well maybe because it's a total nonsense argument? Unless you actually want to kill all road transport and everything reliant on it, which is effectively everything, in which case I also think it's clear why you're not getting any replies.
You are missing that the cost of bike lanes isn't just in constructing and maintaining them. Adding bike lanes in cities means dropping car lanes because there's not enough space. That ends up creating potentially huge opportunity costs.
Anyone who has done any amount of virtual traffic engineering (aka: Factorio, City Skylines, OpenTTD) knows that intersections are where the bottlenecks are.
Its incredibly difficult to design a max-throughput intersection. Roads have a huge amount of throughput, most "traffic" just gets stuck at offramps and traffic lights.
Narrowing a road to make room for bike lanes is a lower cost than people might think. If you're all going to get stuck at the next intersection anyway, it doesn't matter if you're a 2-lane, 4-lane, or 8-lane road.
It’s not all about throughput. Taking away car lanes in favor of bike lanes usually takes away parking as well.
While that certainly has the desired effect of reducing car traffic to the area, it also increases the difficulty and expense of travel to the area. We’re seeing this in Oakland now, where they’re putting in bike lanes and taking away parking, while simultaneously doing nothing about the limited public transportation system.
If you want to reduce vehicle traffic without seriously impacting the shops and restaurants in the area, you have to use both knobs available to increase people’s use of public transportation: make it harder and more expensive to drive a car, while also making it easier (and, preferably, cheaper as well) to take transit. One without the other is a disaster.
I mean, or you can ride a bike in these new bike lanes in one of the flattest and temperate climates in the US?
Oakland is littered with cars along roads in every neighborhood you go on, and the police barely enforce anything resembling traffic code (due partially to complicated historical reasons). In some neighborhoods, I've seen duplexes with more land area in cars than living space (so is it a wonder that poorer people here live in their cars when it's so easy to own and park a car?)
A bike lane or two makes it cheaper for most folks (yes including the folks living in the pop-up Oakland housing shelters, they own a lot of bikes) to safely move around, and reduces traffic from our generally saturated roads. Given the limited paving budget here (and how tectonically active the hills are), it's a wonder that bike infra has taken so long.
Moreover, the heavy private vehicular traffic in the area makes it very difficult for buses to navigate their routes in a timely manner, and taking parking off the road for bike lanes and BRT is a much cheaper way of enabling transit in the area that laying down rail.
Sure, you can ride a bike. Now, tell me how you would transport groceries for a family of 4, or how you transport the kids to doctor's appointments, for instance. What about people who physically can't ride a bike? What if I'm coming from 15 miles away?
Surely as someone from the area you've seen the countless folks with cargo bikes transporting their kids? I live 1.5 mi. away from my grocery and I take panniers and shop for a family of 2 (though I understand that kids need a lot more things than adults do, so this isn't an apples-to-apples comparison). And if you're coming from 15 mi. away, you're a guest, not a resident, so either take transit and a bike share or circle the block for parking. I don't demand a house in your yard, and neither should you demand a parking spot in mine. Also, what about the folks that physically can't drive a car but can ride a bike, or the folks with poor reflexes or vision that should not be allowed to drive and yet are given a pass in the US because it's so driving centric?
But intersections also suffer if you give them less lanes. Say for each direction you have two lanes in your intersection, one for people going straight or turning right and one for people turning left. To get bike lanes, there’s no choice but to drop the lane for left turns (and my city has done this in a few places). Now you either forbid left turns completely on that intersection or every left turning car will completely stop traffic until it can move. Either way you’re creating a total mess.
One effect that I’ve seen pretty consistently is that adding traffic lanes to a single-lane local road almost always slows down traffic. This is because every intersection needs a stop light.
> it doesn't matter if you're a 2-lane, 4-lane, or 8-lane road
If you halve the capacity of the road, you're just going to spread the same cars (and congestion) among twice as many lights...and make traffic far worse.
Depends. My commute home from my office has a 6km of a three-lane road and then a single traffic light. The road never gets backed up more than a couple km from the traffic light, so even dropping it to a single lane wouldn't make any real difference to the throughput. The speed you drive on the three-lane road also makes no real difference to the throughput as long as you get the same amount of cars through the traffic light at each cycle.
The bit about speed prior to lights was meant to be separate from the bit about # of lanes. To clarify - I mean, e.g. that when there's 5km of free-flowing traffic before the lights, and then 1km of congestion, it doesn't matter how fast you drive for those 5km as long as it doesn't delay your passage through the lights. I could halve my speed from the speed limit for those 5km and still arrive at the congestion at the lights before it's my turn to go through them.
I wasn’t missing that, I just wasn’t addressing it; I was just addressing how to assess maintenance taxes. If there are other costs of having the road there, like its real estate usage, I agree that’s another factor to consider.
Bike lanes can handle more traffic per surface area than car lanes. Utilization is unfortunately low in most areas, but capacity wise it’s a clear net gain for city centers.
Oddly enough, sidewalks are the most efficient use of space, but require good public transportation and extreme density to reach that threshold.
In Oslo, Norway the city builds a lot of bike lines . It narrowed streets for cars or removed parking places. I talked with a few folks with cars in the city and their typical response that it made them to get work faster with a car. Surely they have to walk more to a parking spot, but after that they drive faster through the city. Apparently street parking creates a lot of congestion.
Perhaps a inverse tax tied to economic output of that vehicle. The higher the economic contribution of the vehicle, the lower the tax. So a recreational cyclist pays more than a delivery truck because the delivery truck is contributing to the economy and not simply joyriding.
That is way too arbitrary. Just because money exchanged hands at some point doesn't mean the transportation is a net benefit or should be encouraged and everything else discouraged.
Besides, I think the economy would be much healthier if everyone was riding their bike recreationally (healthy bodies, healthy minds). And a much bigger boost to the economy than a delivery truck driving 10 miles to deliver a $2 package.
That seems too easy to game, and the system might have low compliance. Who's to say when a person is joyriding vs commuting to work on a bicycle? If we're taxing based on the economic output (which we hopefully already are via income/sales taxes), does the time value of goods being transported now get included in the calculation?
On the topic of tire wear, I find that my rear bicycle tire will last roughly 3000 miles/4800 kilometers. Even summer performance tires on cars will last about 8000 miles (and most all season tires will go for at least 20,000 miles).
I recall a buddy proselytizing on the virtues of rotating your bike tires every couple thousand miles, which for that group was about once a year (and replace in the spring)
My issue with that is how your control comes from the front tire on bicycles. Anytime I have a tire issue the front tire gets the newest rubber. Rotating tires is just spreading the wear and reduced traction to your steering tire.
What I normally do when the rear tire is worn, is get a new tire, mount it on the front and move the original front tire to the rear. Even after 3000 miles of riding, my front tire doesn't show much wear at all. The rear tire, on the other hand, will have virtually no tread left.
After thinking about it a bit, I believe he was suggesting rotating at 1k, and replacing the tires every 2k. Which would still leave an awful lot of tread, but also be a more aggressive replacement period than most people would do.
I remember a hitchhiking ride in France with a man working in the building and infrastructure industry telling me about these figures, and the intense lobbying against transporting goods on rails...
The subway has tires for technical reasons. Stations in the Paris subway are close enough that better acceleration times have a significant impact on travel time and peak-hour capacity.
If they were willing to retool, you’d think they’d just go with a maglev monorail design. Those have the capacity for the instantaneous acceleration of a railgun.
That would be a pretty rough ride. I wouldn't want to be a straphanger on one of those. The turns would be uncomfortable as well in a railgun railway car.
At Michelin, we're more than just Green guides, we put our tires on the subway cars and encourage protesters to use ours for all their tire fire needs.
In January there was this report: Microscopic pieces of plastic have been discovered in the most remote locations, from the depths of the ocean to Arctic ice. Another place that plastic is appearing is inside our bodies. We’re breathing microplastic, eating it and drinking plastic-infused water every day.Plastic does not biodegrade. Instead, it breaks down into smaller pieces, and ultimately ends up everywhere, including in the food chain. Pieces that are less than five millimeters in length, around the size of a sesame seed, are called “microplastics.” https://graphics.reuters.com/ENVIRONMENT-PLASTIC/0100B4TF2MQ...
On Germany the best lobby work to put transportation on truck instead of rail is done by DB, German Railroads, with their freight services. Compared to trucking you can easily double lead times, increase costs per ton and decrease trackability and reliability.
Lower costs for the customers and higher reliability when you ship by truck means rail is not really a consideration even though it would be better for everyone if it actually worked.
A family member was a civil engineer in the Federal Highway Administration for many decades, specifically in concrete pavement design, and remained an a technical career path the whole time.
He had many war stories to tell related to the trucking industry. In one, they had developed a scale that could measure the weight per axle of vehicles on the roadway without requiring the vehicles to slow down. They wanted to embed these in a few places to prove how bad things really were with overloaded trucks.
The trucking industry bought off some congress critters who would only allow them to put the scale at one clearly marked location on an interstate, in one lane. The lane next to the scale lane was crushed by all the trucks driving in that lane to avoid the scale.
I don't doubt it, we have a local road here that has been fine, but this year they decided to drive a lot of truck loads of snow to save a skiing event from another city up that road and now it's completely destroyed and it needs new pavement and possibly new foundations in several places.
Trucks should really only be a last resort for the last mile to the store and the rest should be sent by rail or boat and loaded onto trucks if necessary.
They also have huge externalities when it comes to damage to other cars, when my car is hit by rocks on the road it is always coming from a truck.
We have such roads here in NY called parkways, cars only no busses or trucks. Absolute disasters. I frequently take the Belt parkway in NYC to long island via the southern state parkway. That thing looks like it was carpet bombed. They have been patching massive delaminations and joint failures on a weekly basis all winter and we have barely had any freezing weather or snow (it's been spring all winter.) One delam by an interchange was so deep that it took out a few car tires with low side walls.
I was annoyed at these failures and some light reading. You can make more robust roads by making them thicker with a sturdy foundation. Of course this comes at a much higher cost. For example, the autobahn pavement thickness is 27 inches. Whereas by me they mill a few inches off the top of whatever sad situation in below and top it with another 4 inches or so. This is because robust roads are costly and there are so many other things in a muni budget which need attention. So they compromise and lay down a cheap road.
I drive on one of the routes used by lorries servicing the UK's largest container port. The roads are visibly buckled in the lanes the lorries use. You can feel your car uncomfortably slotting into the grooves. It seems insane to me to use the roads for that. A railway seems like a complete no brainer, especially considering these are containers and easily loaded.
But at least the weight of a lorry consists of mostly the goods being transported. The more pertinent comparison is a bicycle vs single-occupant "SUV". Unlike lorries, those things are tearing up smaller roads in town centres making the roads barely usable by smaller cars, let alone bicycles, despite the fact that cyclists contribute equally to road maintenance.
Those SUVs also require larger brakes which is a major non-exhaust emission. It's high time to start taxing these vehicles heavily and I think using the fourth power of axle load seems like a sensible way to do it.
I'd be interested to know how wear scales with tyre pressure.
The tyre pressure exactly matches the pressure on one spot on the road surface, so if pressure is higher, a smaller area of the road receives more downward force, causing it to bend and flex, and eventually break up.
> I'd be interested to know how wear scales with tyre pressure.
Apparently not in any way relevance in face of the fourth power rule, as road authorities worldwide just use the 4th power rule for road wear estimates, without accounting for minor factors (type of axles, axle arrangement, surface contact and suspension systems).
There's no "why", it's a rule of thumb / estimate called the "fourth power rule" (or "fourth power law" but there are other unrelated fourth power laws) established experimentally in the late 50s / early 60s by the AASHO. Basically they built a bunch of roads to the same specifications, drove streams of vehicles through and monitored pavement deterioration.
I'll take your off-topic a step further ;) A couple days ago on one of the NPR shows they interviewed a long-haul truck driver. At one point he said (paraphrasing), "If you bought physical goods, it was transported by truck."
Given the amount of consumption (of physical goods) that's a significant amount of tire wear.
Unless you walked naked out into the woods and built your life entirely from found materials, literally everything in your life was at some point or another hauled by a truck.
Everything.
This is not a hyperbolic way to make an argument, it's the truth. Sometimes you'll have to go pretty far back the chain of events, maybe as far as raw materials, but at some point (probably several) X was on a truck for any X.
A hippie commune that grow all their own food living off the grid? Their clothes, their tools, the paint on their house, it all rode on trucks.
Two-ish years ago truckers in Brazil went on a strike to protest increased gas prices and corruption and it only took three days before the president ordered the military to force the trucks into moving again. That's how hard it hits if trucks stop moving.
The military couldn't do shit though because the trucks hauling the diesel powering the military vehicles were part of the protest so they got nowhere.
If all the trucks stop right this second, we'll be living in post-apocalyptic chaos by Friday. No joke.
Right but people buying F-150s are not buying Teslas. The use case is quite different. My Subaru Outback (a rather large car in comparison to the Tesla) is 3,600 lbs. But I doubt the increase in weight is a huge factor in environmental concerns.
> Right but people buying F-150s are not buying Teslas. The use case is quite different.
Have you been to a Texas city? They're full of F-150s driving around a single person and an empty bed on paved roads.
Sure, farmers and contractors use trucks as trucks, but thousands of people use them as commuter cars. Most pickup trucks are used as trucks once in a blue moon.
Isn’t Model S closer in size to Camry? A Corolla is closer to model 3 size and more like 2900lbs. The P90D with less range than that 100lbs of gas Camry is 5000lbs.
Interior volume of Camry is 115 cu ft (27lbs per interior cubic foot without gas, some marginal amount more with the same amount of gas as P90D's range, which only takes around 60-80lbs of gas or so).
Model S P90D is 120 cu ft (41lbs per interior cubic foot).
They fitted brand new tires and called it a read world test, as if people get new tires every week. Then they measured particulate weight and compared it to ICE emission regulation as if weight was the deciding factor: 5800 ug of rubber particles vs 4.5 ug of PM soot. The rubber could be 1x 5g chunk or 1000x 1ug or whatever. New cars produce mostly small soot, so 4.5 ug can be about 10 000 000 particles¹.
I'm not saying non-exhaust emissions are irrelevant, but I am quite sure exhaust is a much bigger issue, overly so in eastern EU, where people often even remove DP filters and enforcement is lacking.
> Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles.
So this is based on n=1, very suspicious.
If tires really were this big a source of PM emissions then how would levels in US cities gone down through vehicle pollution control measures. Something is not adding up here.
At that rate you would burn through the whole set of tires in less than 50,000km, so how is it possible? Could it be those nubs on new tires are accounting for a majority of the waste up front?
Yes. A high UTQG rating will mean your tires will last forever at the expense of traction, road noise, etc. The last set of tires I bought at Costco lasted 70k miles, but also increased wet stopping distance and introduced a roar to cabin noise. My latest set have a UTQG near 0 and will only last about 10k miles but they make no noise and have insane amounts of grip (think race car tire)
If you drive less and have separate summer/winter tires, it has the odd side-effect of making long-wear tires not worthwhile, as the life of the tread depth will exceed the life of the rubber due to age.
I drive about 3.5k miles a year, the OEM tires would have given me 70k miles but I would have never got there. the michelin pilot sport 4s where $5 more per tire and would survive just about 7 years (i'm planning 3-4 with the occasional track day). the tradeoff was DEFINITELY worth it, but now i'm deathly afraid of potholes and road hazards lol!
(after 1000 miles on the MP4S you're already more than 1/16th worn and would need to replace the entire set to keep the AWD system happy)
I've done 60k miles (96 kms) on my current Michelin Cross Climate tyres. The front ones are going to need replacing soon; but the rear ones are still good.
That is on a 2008 Toyota Prius so not the lightest of cars.
Good tires driving on mostly paved roads should last at least 120k kms. In the US, you pay $120-200 per tire for those, but they also come with a warranty that will replace them for free if they wear out before the distance advertised.
That's not how treadwear warranties work. They're not "replace them for free"; they're pro-rated, and there are all kinds of restrictions and limitations.
My understanding was always that tires produce a lot of particulates but they are fairly large and heavy; most of them fall out of the air very quickly.
If that's true it could be true that cars emit lots of PM from tyre wear but must of it never reaches detectors and can reasonably be ignored. That doesn't necessarily invalidate the overall point: that we reduced PM from exhaust enough that other still unregulated sources are better targets for future reduction efforts.
Fall out of the air. Into the sewers. Then into the rivers, and then the sea, where they are broken up into microplastics and return in the food chain.
Having lived next to a freeway, I found everything in my apartment covered with a sticky black dust that took hours to remove. I found embedded on books and other items years later. So, I think this has been true for a long time.
What I didn’t find mentioned is these emissions were more or less localized to a small distance from the road. For example when I moved it went away. That said I’m sure it’s a nightmare for the watershed.
We moved a young coworker into a first floor appt in downtown and there was black soot on all the windowsills. I taught him about soap and vinegar and we suggested an air filter and being judicious with opening the windows, or finding a window fan with a prefilter.
It had just not occurred to me that the busses and trucks were pumping out that much soot in the modern era.
All these articles are important, but they end up missing the point of the auto industries weightiest concern.
At the end of the day, it really comes down to the weight of the vehicles. There is absolutely zero justification for any standard-use car to weigh more than 3,200 pounds, and that's for a SUV.
More weight affects EVERYTHING.
Material logistics/sourcing/shipping/construction costs and emissions/waste-disposal, end-product shipping/distribution/operating-costs and emissions/repairs/waste-disposal, as well as infrastructure construction/maintenance. That's just hard costs. I could go on in more granular fashion and add soft costs like less traffic and less road noise as well.
I drive a very loaded gasoline powered Fiesta hatchback. It's got cruise control, a great entertainment system with car play, even stupid neon lighting I didn't want. It weighs only 2,600 pounds and even though it isn't fast, I don't have any issues getting up to speed. My mileage is consistently 29 in LA traffic and 34 driving fast on long highway trips. It's nearly 2 feet (22 inches!!) shorter than a Camry and I can park it basically anywhere. Because it weighs so little, tires last forever. It cost me less than $20,000 brand new. My point is that a freaking heavy and large 3,400lb sedan, or 4,500lb SUV is 100% supremely unnecessary.
Multiply hundreds or thousands of weight savings per-car over millions and millions of new cars sold in the US alone would insanely positive and tangential effects on the planet. Eventually those gains would reach the economy and infrastructure too.
It just infuriates me that there is a relatively simple way to mitigate so many issues and it's so blatantly ignored or not even known.
Isn't one of the biggest reasons to drive a very large car safety? Unless everyone starts driving light weight cars, it seems to me that anyone who does would be putting themselves at risk in the case of an accident.
I'm not so much meaning safety technology as raw size. To give an extreme, in a collision between a full size SUV and a Smart Car I would expect the driver of the SUV to be more likely to survive.
Unnecessary for you and your usage, but there a lot of situations, environments, and applications where a heavier, larger vehicle is necessary. If you live rural you aren't driving a small Fiesta hatchback everywhere. If you have a large family, an SUV is a basic requirement of modern living to move the family around.
Conversely if you live in a city with tight quarters as a single person with no kids, an SUV or pickup may not be necessary at all.
There is a reason we don't dictate choice or consumption with something as necessary and basic as transportation because it isn't one size fits all. People buy what they generally need.
"Basic requirement for modern living" – what an absurd claim to justify a SUV. I wonder how people in most non-US countries even get by, if the basic necessities of life aren’t met. /s
It's totally understandable that someone as individual contractor might need a bulky pickup to haul construction materials, and I don't take issue with that.
As for SUVs they will obviously be heavier, sure, but how much more value does a Cadillac Escalade provide at over 5,000 pounds compared to an XT4 that weighs, 1,600lbs less? And then how frequently is that value actually utilized?
Rubbish. Go to South Africa and they're driving around in small hatchbacks. Farmers drive pickups (bakkies), but normally sized ones. There's simply no way those monstrous things are a "basic requirement". You are so out of touch with how most people live.
The rural poor still drive Cavaiers and whatnot. You absolutely "can" drive a Fiesta (or some other compact) if you live somewhere rural. It just is a standard of living below what most people expect in 2020.
People have the money to buy things that they want and makes their lives easier so it's no surprise that they do.
I also wonder about pollution from shoes with plastic soles - pretty much every pair I have ever owned, the sole just wears out gradually until there's nothing left. Where does this plastic go? It's just ground into fine powder and stays on our pavements? Is then washed with rainwater and goes into our soil? How come this isn't a problem yet? Or if it is - why isn't anyone talking about it?
Because plastic is not a significant pollutant. What's next, we're going to remove soil from the environment? Soil is full of, mold, bacteria, virus, metals, minerals, fungi, urine, feces, decomposed insects, thousands of chemicals like rust, alumina, silica, heavy metals, many carcinogens, lung irritants etc. It can give you "Farmer ’s Lung" and it's _everywhere_ in nature. Plastic is quite clean and tame by comparison.
Everything is killing us, but some things faster than others and so we have to prioritize, but hedge. Woodworkers have dust collection systems, air exchangers, and occasionally respirators, so they don’t get something akin to asbestosis from sawdust. What escapes gets processed by soil fungi so not a big problem.
Microplastics have a possibility to do bad things to us over the long run by accumulating in our soils, and playing out like a slow train wreck. I have my fingers crossed that saprophytic fungi are already on the case. But it’d be good if someone gave Paul Stamets a research grant.
The water situation is of more immediate concern, and feels more hopeless to a two-rungs-above-armchair environmentalist like myself.
Probably true by themselves, although we just don’t know how many PBAs we haven’t figured out yet.
Plastics have a habit of accumulating some pretty bad chemicals like petrochemicals, PCBs, and possibly dioxins but don’t quote me on that one. So ingesting plastic in a lab setting and plastic in the environment may have quite different outcomes.
I honestly believe the anti-plastic movement as well as the recycling movement are at best mass confusion and at worst a way for corporations to divert environmentalists energy away from focus on reducing consumption, reducing travel and reducing human sprawl which would have actual environmental benefits but would hit business growth much more than "buying reusable containers".
This whole, I travel thousands of miles every year but that's ok because I bought a reusable bag shows a complete lack of proportion and perspective. On top of this, the reusable bags take more resources to produce and often they aren't machine washable so they're thrown out anyways once they're soiled, but that doesn't matter because both carrying options have insignificant impact to the environment compared to most forms of consumption.
The claims here seem dubious. They tested one type of brand new tire. Then they conclude that "high-quality" tires are somehow better without providing any evidence to support that claim. While tires may very well be a source of pollution I have to wonder where the money for the work came from.
Tread wear isn't a measure of quality, it's a measure of the how much 'grip' a tire is designed to have. High performance tires are softer to grip better, but wear out much much faster than tires designed for higher mileage. The higher mileage tires have worse performance characteristics - greater stopping distance, etc.
Tyres are designed on a performance - life continuum. High performance means softer rubber, with better grip, but thus lower life. Long life means harder rubber, with less grip, thusly reduced performance.
At least in the US, we have Uniform Tire Quality Grading [0]. According to Consumer Reports, which tested at least 47 tires, "most tires should live up to their mileage warranty claims"[1].
I've seen "high-quality" tires with a very low treadwear rating and I've seen "low-quality" or "cheap" tires with a very high treadwear rating. But the press release only mentions "high-quality" without defining "quality" at all. Which adds to the dubious nature of the claims.
they're also measuring vastly more "emissions" over the life of the tire than there is material in the tires, so it appears that what they're actually measuring is the asphalt dust that's being created by the interaction between the road surface and the tire - a longer-wearing tire would presumably be harder material and cause slightly more road wear as a trade-off to less tire wear, so if they had actually tested it a higher-quality tire might cause more of what they're classing as emissions.
but you can't really make an assumption either way when you've only measured on a sample size of one.
It's true that they weakened the wording in that section of the body, but the description of the actual research does make it sound like the factor of 1,000 was a typical case, not the worst case:
> Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles.
>
> Compared with regulated exhaust emission limits of 4.5 milligrams per kilometer, the completely unregulated tyre wear emission is higher by a factor of over 1,000.
Of course, this assumes that the tyre particles captured by their methodology are (on average) equally bad as exhaust particles, and maybe brand-new tyres wear especially quickly or something. It does seem hard to square the factor of 1000 from this study with the estimate that non-exhaust emissions account for a mere 60% (rather than 99.9%) of PM2.5 emissions.
Would be curious to hear from anyone who understands emissions testing better.
Life of car tyre is ~40e3 km. 5.8g * 40e3km = 232 kg. Or 58 kg per tyre. A new tyre weighs about 8kg. I guess it might loose 3kg. So I think they've over estimated by about 20x.
Keep in mind too that a tire that has no usable tread life left is still quite heavy compared to the full tread life, new, version because there is so much left for the sidewall and the steel belts inside of the tire. They must be getting this number from measuring something else in addition to the tire
Also headline: "pollution", and article "harmful particle matter from tyres". The study was of particulate emissions only, where when we generally think of "car pollution" we're talking about carbon or unburned hydrocarbons or toxins, not smoke. And the comparison was to "what comes out of a car's exhaust", when the overwhelming contributor to the particulate composition of smog is reactions in the atmosphere and not the stuff in the pipe.
Not a good headline at all. But still, no doubt tire pollution is reasonable significant and we should all be driving less anyway.
"Smoke" is underselling it a bit. Tyre wear creates PM2.5, which is toxic. I don't consider that outright misleading in comparison to misstating an upper bound as a tight bound.
As described in the article, the number they used for the "1000x" comparison wasn't PM2.5 due to car exhaust. It was PM2.5 IN car exhaust, which is quite literally the thing we call "smoke". The vast majority of smog particles due to automobile traffic appear in the atmosphere as reaction products, they aren't in the exhaust.
Presumably they meant 5.8 milligrams/km rather than grams - thats 290 grams over 50,000km.
The following literature review(2014) mentions an estimate of 0.1-10% tyre wear becoming airborne - because the majority is relatively large particles:
I have a respiratory illness from air pollution, and never had problem with tire pollution created by electric vehicles. Even with LNG vehicles I feel somewhat better.
Tires may create big particulates, but they are easy to filter. The small molecules that I am sensitive to are extremely hard to filter from the air.
> Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles.
>Compared with regulated exhaust emission limits of 4.5 milligrams per kilometer, the completely unregulated tyre wear emission is higher by a factor of over 1,000.
This is approximately as reasonable as declaring that a crossbow is more dangerous than a gun because it fires a heavier projectile. How large are the particles? What's their expected lifetime in the atmosphere? What proportion are smaller than 10 micron? 2.5 micron?
Considering a mazda with tyre size of 215/45 R18 with 1/4inch useable tread depth, that lasts 30K miles:
The mm^3 of rubber lost over lifetime (circumference * how wide the tire is * tyre tread depth) is approximately 2375922.431
Considering density of rubber at 650kg/m3, the weight lost over 30,000 miles is 1.54kg, which equates to 31mg/km and nowhere near 5g/km as claimed in the article. What am I missing?
So to visualize this I'm thinking of a rectangle 2.5 feet long, 8 inches wide, and a half-inch thick times 4. That is what comes off my tires every 5 years so that I have to replace them. Every set of tires sold is to replace that.
The numbers don't seem to add up. If an average set of tires lasts (roughly) 50,000km to 100,000km, and the average tire weights around 10kg, and you have 4 tires, then the (totally unrealistic) maximum loss per km is 4 * 10 * 1000 / 75,000 gms/km. This is 0.5g/km (and it assumed that there was no tire left). While these numbers are rough, I don't see any way to get to 5.8gm/km as quoted in the article. The brake pads aren't going to contribute all the rest (they aren't that heavy to start with).
What about the road surface? Maybe you can erode 1cm of surface over 10 years with 2,000 vehicles per hour (average down to 20,000 per day. Volume eroded (per km) in cc is 400 (width) * 1 * 100,000 (length) = 4e7 cc. Density is around 2.5 gm/cc. Mass eroded is 1e8 gms. Cars is 20,000 * 10 * 365 = 73e6. Amount eroded by each car is around 1.3gm/km.
Maybe someone could check my assumptions (and my math), but I still don't believe the numbers in the linked article.
To look at it the other direction, 5.8 g/km times 75,000 km means they have to somehow produce 435 kg of pollution per set of tires.
Without some more explanation (are they building some kind of model to extrapolate to the entire supply chain?) that seems more than a little implausible. It seems most likely from the context that they are measuring shedding of brand new tires and trying to pass that off as a representative value.
I guess the idea is that it’s a contributor to the acute dose in the car’s immediate vicinity, but without that context it seems like another misleading detail.
> Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles.
Could it be that tire wear drops off? Initially it's shedding a lot, I dunno, due to surface layer being porous or something, and then the wear drops off to the normal rate?
Yes, the tires wear, and the wear can be easily measured by the mass difference between a new tire, worn tire, divided by the distance. Plausible that the total wear is 1-3 orders of magnitude total mass greater than modern tailpipe emissions.
A huge question that is never answered is how much of those worn particles actually become airborne, how many stay airborne for how long, and what is their effect on organisms breathing them.
While the Precautionary Principle says we should assume harm, this entire article seems to assume that every microgram is automatically the most harmful possible pollutant, which is likely untrue, unnecessarily alarmist, and undermines their thesis.
Question is, what is the dosing level that would cause harm, and what are the routes that this material takes that might rise to such a level, vs how much is, e.g., stuck on the pavement and washed into the ditch with every rain?
Exactly, so while the authors are ringing alarms about the particles from a health POV, they might be a irrelevant to that threat, but a major threat to certain ecosystems, or nothing at all.
Certainly bears good investigation, but far too soon for conclusions (an I'm usually biased towards acting based on Precautionary Principle, but this just seems far too indirect to even make assumptions, let alone conclusions).
I think we know that living near major roads is bad for you. So to figure out the dose you'd have to measure it at different distances. Volume and type of traffic. If you live near a major road you probably want to run an air cleaner with a hepa filter and not go outside to much or on busy days.
For those people wondering about what percentage of PM2.5 and PM10 are caused by non-exhaust emissions.
"NEEs are currently believed to constitute the majority of primary particulate matter from road transport, 60 percent of PM2.5 and 73 percent of PM10 – and in its 2019 report ‘Non-Exhaust Emissions from Road Traffic’ by the UK Government’s Air Quality Expert Group (AQEG), it recommended that NEE are immediately recognised as a source of ambient concentrations of airborne particulate matter, even for vehicles with zero exhaust emissions of particles – such as EVs."
This talks specifically about particle pollution ( not CO2 emissions ) which has already been largely regulated out, "up to" 1000x of a very small amount can still be quite insignificant.
Given the misleading nature of the press release title I think I'll avoid reading the actual result and mentally mark "Emission analytics" as one of those companies.
This is the perfect opportunity to link people to Robert Heineken’s story: the Roads Must Roll. In it, there are a series of road towns, where roads are more like moving sidewalks. Very neat stuff, I read it as a teenager and then re-listened to a great audiobook version recently too (bundled with the man who sold the moon, which is the prophecy foretelling of Elon musk)
I used to live about 4 blocks from CA-17 (a 6 lane freeway) and when we’d leave the windows open a layer of black soot would form on the window sill after a few hours. I always thought that this soot was a combination of rubber from tires and diesel soot. When we moved away, we can leave our windows open and there’s no black soot. I’ve always felt like living near the freeway was like living next door to a heavily polluting factory.
OT: I was thinking: Imagine how easy self driving trains are to make. Then I naively pondered if air filled tires are all that efficient. I cant imagine bending the rubber gives back a lot of energy? I just looked it up: "An average truck gets around 150 ton-miles per gallon of diesel. Trains get around 600 ton-miles per gallon."
I live next to a very busy road (6-lane). When I moved in, the closets were filled with black stains. My brother-in-law cleaned it and said he never saw that kind of dirt. The closets are dirty again.
As time passed I also never encountered that amount of dust. The dust was also extremely different from the dust when I lived in the forest, dark colored and plentiful.
It accumulates very quickly, it gets abandoned-house-dusty in a week.
My breathing also got worse compared to the forest, especially during nights. So there's definitely something dusty around the road.
It was also quite interesting to see that the bathroom gets dusty as quickly too, despite being closed most of the time. It's like the whole ventilation system of the building naturally permeates dust.
If you have a central air heating system like most houses do, you should add a filter near the fan. You won't catch all the dust, but you'll collect a lot of it, making your air healthier to live in
When I first moved to the SF bay area I didn't have AC in my apartment so I had to leave the windows open during the summer. After a year of leaving them open there was a thick coat of tire dust all along the windowsill since my window faced a road. :x
I had the same experience, in SF too. Second floor corner apartment on Fell St, a wide and busy road along the park. The windowsills on that side accumulated black dust unlike the other side of the corner.
In the 70s I live in an apartment adjacent to Interstate H-1 in Honolulu. Same experience. Lanai furniture black. Don't know if tire or exhaust caused, but it was black and disturbing and probably in my lungs.
The German Post designed the Streetscooter a while back which is an electric delivery van. They also claim "zero fine dust driving". But how does that work? It is quite hard to have a fully closed system so no particles can escape. Well, their solution is quite clever: They are filtering the air in general, so can also consume particles emitted from other cars, even when the vehicle is not moving. So they could even get to net negative fine dust emissions :)
Assuming that this really is a problem (which other comments have thrown into doubt), I see potential conflicts between vehicle safety and fixing this.
One obvious solution is harder tires that don't wear as much. But these tend to have worse grip, which means worse braking performance (and cornering, etc.).
They also mentioned that reducing the weight of cars would help, but one of the reasons cars have gotten heavier over the last few decades is the addition of a bunch of safety equipment.
This article, and the whole website looks so suspicious. Quotes come mostly from its own organization, "Emission Analytics", and there is no reference to an existing or upcoming publication.
In addition, and I realize I'm nitpicking, the stock photo, the composition of the copy and the general... feel of the website seems off.
The overall effect is to make me actively distrust their conclusions and want to ask about their agenda and source of funding.
If the idea is to focus on tires, then why not just look at how many tires are manufactured each year? 100% of tires end up polluting something, somewhere.
Or, again if the focus is tire wear, there must be pretty good data about how much of a tire gets worn off before replacement, and how often they're replaced. It doesn't seem like it should be very complex to calculate how much tire is being emitted due to road wear.
Fake news. Smaller particles from exhaust are way worse for you than larger particles from tires. Within a category like PM2.5, mass is a terrible metric. A given mass of fuel exhaust will contain orders of magnitude more particles because they are tinier. Smaller particles can penetrate deeper into your lungs and can go into your bloodstream.
Tires contain fossil fuel products like carbon black and synthetic rubber.
The roadway contains bitumen, another fossil fuel product.
The numbers in this experiment seem dubious and are probably not representative, but they do reflect our over-dependence on refined petroleum. We have to find new ways to make these things.
If someone had told you that this would be the case in the 1960s, they probably would have jumped for joy. It’s more a positive signal for how much emissions technology has advanced.
Obviously it’s something worth looking at and improving, still, but it’s definitely not a sign that things are getting worse, but rather the opposite.
No. When things roll very tiny pieces break off both the rolling thing and the thing rolled over. If we want to travel by rolling (which seems like a yes) along the ground then that's going to produce PM 2.5 air pollution.
Flying is definitely worse, for at least the medium term and perhaps forever, and magnetic levitation is so expensive you're just not going to do it at scale.
The effect from pushing a stroller will be greatly (much more than linearly) smaller than from a goods delivery truck or a railway train, but it's there. We just have to consider this when deciding what's a good idea.
The claim is this:
> "Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles."
It does not seem to be a mistake:
> "Compared with regulated exhaust emission limits of 4.5 milligrams per kilometer, the completely unregulated tyre wear emission is higher by a factor of over 1,000."
A tire might way up to 15 kilograms for a 20 inch type. Lets assume 10 kilograms for a normal tire which is on the high side. 4 tires is 40 kilograms. Even if we assume half of the particals are not coming from the tire (but from where?). That still leaves 40,000 / 2.9 = 13793 kilometers for the tires to be completly consumed (weighing nothing anymore). That is definitely not happening.
So without an explanation on where the matter is coming from this does not read right.