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Car tires shed a quarter of all microplastics in the environment (phys.org)
102 points by geox 2 hours ago | hide | past | web | 93 comments | favorite





This reminded me of an old article I read about this from `Straight Dope` years ago (2006 in fact!)[0].

> Pollution studies in the Los Angeles basin in the 1980s concluded that more than five tons of breathable tire dust were released into the atmosphere there each day, and there’s no reason to think that figure’s gone down since.

[0] https://www.straightdope.com/21343778/when-the-rubber-meets-...


Five tons sounds like a lot. But on the other hand, the Los Angeles basin sounds pretty big. (a quick check suggests it is about 1200 square miles)

The AQI there looks good.


Don't assume that the distribution is uniform.

We need to start making manufacturers pay for their negative externalities.

Manufacturers aren’t making tires and then turning them into microplastics alone. Pretending consumers aren’t part of the problem is misleading.

We could add fees to tire manufacturers, but be honest: It will just get added to the price of the tire. That’s fine if the goal is economic incentives or funding remediation, but people start to lose interest in such fines as soon as they realize it comes out of their own pockets instead of from some imagined slush fund manufacturers are keeping to themselves. (See similar problems with conversations about tariffs, which people only like until they realize they will be paying for them.)


Manufacture in country A and sell in country B. Or vice versa.

But never manufacture and sell in the same country, or the government might try to get you to pay for your negative externalities!

And now, there’s this annoying predicament where as you introduce more laws and more enforcement, you only cripple your own economy and rarely cause any significant improvement along the lines of what you hope. Look at Australia — we have all these appliance safety laws, but all of the appliances are made overseas and there’s no good point for the government to inspect and enforce compliance with those laws. I just bought a generic vacuum sealer from an online shop the other day. It was cheaper than buying at a brick & mortar store, even with delivery, and it definitely does not comply with Australia safety standards.

We’ve killed our local industry, and our economy is suffering for it. I don’t think the answer is to remove the safety/etc laws, but instead to tax all imports enormously. Be aggressive and unfair so that local industry is immediately viable. It’ll be painful, but it’s what most countries need. Comparative advantage turned out to be a terrible basis for international trade.


This is what tariffs do well. When you tax a local manufacturer, you impose an equal tariff on imports.

That only makes it fair within your country, but it doesn't remove the self-crippling effects.

That is why international agreements like the Montreal Protocol are so important.

That was 40 years ago. In the interim capitalism has won and democracy is failing. Agreements like Montreal will never happen again, at least not in our lifetimes.

Look no further than the failure of the Paris Agreement and the ascent of authoritarianism worldwide. No one cares about environmental agreements, certainly not those in the rarified airs of billionaires, oligarchs, and other captains 9f industry.


...and then the price is added to the price of tyres. Like, where do you think the money is going to go? People can't easily substitute their car use, and there's nothing out there replacing rubber that's road legal, so all you're doing is just adding a tax to car use.

You could do this just as easily with gas taxes, registration fees or any other system.


We need to start making consumers pay for their negative externalities.

Until the externality cost is not baked into product cost it won’t be paid for.


You can tax producers, who will then increase prices. Or you can apply a tax to the product directly, and make it appear that the consumer is paying. But who is actually paying it is a question of tax incidence and a function of demand and supply elasticities.[1]

1: https://en.wikipedia.org/wiki/Tax_incidence


Making manufacturers pay is equivalent to making consumers pay.

The price is passed on to the consumer. The idea of “making manufacturers pay” in commoditized markets like tires is a feel-good myth. Any additional fees will go to the consumer price.


Customers have a price ceiling though.

consumers are already paying heftily… in virginia we pay 4.56% on the value of the vehicle every year plus there is an electic vehicle tax and also million other taxes and fees added.

funny that state with “don’t thread on me” license plate is a bastion of socialism where you are not allowed to own a car but have to pay each year to the state for the right to own the car… the problem of course is all that insane amount of money collected will never be used for anything other than to pay for pensions for former government employees :)


the majority of the pollution probably comes from semi trucks rather than passenger cars, due to the huge weight and number of wheels

Agree, the damage to the road (and the tyres, presumably) is proportional to weight^4.

https://en.wikipedia.org/wiki/Fourth_power_law

> The fourth power law (also known as the fourth power rule) states that the stress on the road caused by a motor vehicle increases in proportion to the fourth power of its axle load


Where i live, 80% of all vehicles are passenger vehicles. I'm not sure that the extra wheels on semis would make up for that difference, especially with the slow increase in size of passenger vehicles.

Something like 98% of ware from road vehicles is caused by semi’s vs 2% from cars and trucks.

20% * 18 = 3.6 vs 80% * 4 = 3.2, so barring some 3rd category semi’s would have more tires. They also have a lot more weight on each of those tires.


Road wear is proportional to weight.

Semi tires are hard, long-lasting compounds relative to soft consumer tires with deep treads and soft rubber.


> Road wear is proportional to weight

No, it scales at the fourth power of the axle weight.


there are 200000x the number of private cars. are you sure?

it's widely accepted that trucks cause the majority of road wear, considering the tire is the softer part in contact there, it seems pretty plausible

I don't have a citation to point to, though!

edit: there are roughly 100x registered passenger cars in the US as semis


Well, given a semi only averages 8x the miles of a car per year, your initial claim is wrong.

https://afdc.energy.gov/data/10309


Road wear depends on weight.

Semi truck tires have hard, slow-wearing compounds.


Semi’s drive 12+ hours a day most days of the year. Passenger cars just go to work and they store and back.

Your estimate isn't even close--you're off by about 4 orders of magnitude.

Fact: In California, the number of trucks is about 300K vs cars at 14M (about 40x).

Fact: California AADT on roads for trucks ranges from a couple of percent up to almost 50%. Very few roads have less than 10% AADT from trucks.

Fact: Damage to roads goes as fourth power of axle load.

Speculation: Given that tires are the primary means to transmit that damage to the roadway, it wouldn't surprise me if the trucks are responsible for the vast majority of tire particulates.

Reference: https://dot.ca.gov/-/media/dot-media/programs/traffic-operat...


Also we need incentives to convince people to choose to drive lighter and smaller cars. Carrots and/or sticks should be considered.

Alternatively, new tire technologies could maybe also solve the problem.


If it's not already obvious, in a lot of places, when regulations are promoted to reduce waste and benefit public/environmental health, a large number of people will get angry and vote for those who'll want to maximize damage just because. If regulations promoting smaller cars were ever suggested in these places, some smiling politician would announce a mandate that vehicles be 5 tons or greater with anything smaller being banned, and compilations of people who worried about the environment would be circulated and heavily mocked online.

Tyre wear is proportional to the fourth power of wheel load; reducing weight per wheel is the key here.

Hiwever, taxing new tyres may be counterproductive, since encouraging folk to keep using their worn tyres is not a good outcome for road safety.


Tyre wear is proportional to the fourth power of wheel load; reducing weight per wheel is the key here.

No, it's not.

You're taking a very loose rule of thumb for road surface wear and baselessly applying it to tires.

Tire wear follows the rubber the tire is made out of. Soft rubber wears faster. Once you control for that it's acceleration and braking loads (i.e. driving style) that dominate. After that is when weight starts mattering.

If what you said was even remotely true then heavy vehicles would get obviously less life out of tires compared to compact cars when in reality they get about the same


> If what you said was even remotely true then heavy vehicles would get obviously less life out of tires compared to compact cars when in reality they get about the same

Are you assuming that the tires of heavy vehicles have the same thickness as lighter vehicles? My bike has much thinner tires than any car, and they can last ten thousand kilometers.


Tires these days are expensive. To make them cheaper, they have reduced quality as well. Likely wearing faster and with worse material

revenue neutral externality taxes are great policy but terrible politics...

I personally doubt that the American government has the power to be able to do such things. Regardless, the incoming administration will under no circumstances impose such restrictions, or push for them to be created. I seem to recall that the previous Trump administration removed restrictions around asbestos, to give you an idea.

Libertarians gonna libertarian. Even if it kills everyone.


> Libertarians gonna libertarian. Even if it kills everyone.

Plenty of blue states have shot down additional taxes. When it comes to pigovian taxes, nearly everyone in America is a libertarian.


Oh, absolutely. If you look at voting records, the overlap between neoliberals and libertarians is incredibly strong in this regard.

EVs are heavier but I suspect the wear is less than you might think because the braking is gentler with regenerative braking, so less wear on the tyres.

Also, there's quite a bit of pollution from break pads and discs, also reduced because of regenerative braking.

I couldn't find numbers though, with a brief bit of googling.


I'd say it's slightly worse, mainly because when you first get the car you tend to launch it a few times and take advantage of all the power. My first set of tires only lasted 27k miles.

After a year you drive normally, I get about 35k miles out of 40k mile rated tires, similar to my old Audi.


I’m not sure it’s gentler or in any way different from a tire’s perspective than braking. If I pull my foot off the one pedal driving, the deceleration I get is fairly comparable to about 3/4 braking in an ICE. (Off the top of my head estimate for illustration purposes only.)

But the tires are made of different materials and are different in other ways too. I can tell you first hand you spend far more on tires if you own an EV. Our model y spends more on tires than our giant diesel pickup, and far more than an ICE of similar size. As for the relative amount of microplastics they emit, I really couldn’t know.

You definitely wear your brake pads out far less with an EV. Just eyeing it though, volumetrically, brake pad wear has to be relatively insignificant compared to tire wear.

I’d guess EVs still emit substantially more tire particles, and fewer from brakes but nowhere close to compensating. But I’d not be shocked to death if someone studies it and you turn out to be right.

And on the plus side, those are probably issues materials science could solve (make the tires out of something benign) whereas EVs emit a lot less of other bad things that I’m sure are not easy to solve or they already would have been.


Your hypothesis then, roughly, is that braking causes more pollution when it's more extreme (since the total braking work being done is at least as great -- in practice much greater because of the increased mass), so smoother braking will reduce tire wear.

I'm inclined to believe an extreme version of that hypothesis -- I doubt 200k miles at 1mph would wear the tread substantially -- but in practice I don't think that's the case. Electric cars tend to replace tires around 10k miles sooner, so the net effect of everything involved (heavier cars, regenerative braking, rich young guys driving faster, mostly city driving, ...) is 15-50% more tire wear per mile.


Pretty sure most wear comes from the back tires (I should say the "power tires" to consider FWD vehicles). Many electric vehicles accelerate quite quickly, which just wears their tires even more.

Braking is braking. If you're stopping in N meters, regardless of how the braking force is applied (regenerative brake vs discs), the tire is the artifact taking the load.

Even then, most cars don't routinely brake as hard as they accelerate.

Motorcycles, with their high performance, are notorious for eating rear tires much faster than front tires, and they can't be rotated.

Then, there's my vehicle, full time 4WD (not AWD, there's a difference), it wears its tires quite evenly in contrast to 2WD/AWD vehicles.


Braking is usually much quicker than accelerating, for almost all vehicles (because brakes can absorb much more energy than engines can output). For this reason, I suspect most particulates are caused by breaking.

> Even then, most cars

I believe you mean most drivers. All of this talk about EV tires wearing faster than ICE tires is driven by people accelerating aggressively simply because they now can.


Electric cars are mostly drive-by-wire, so if the same driver input results in accelerating faster in an EV then I'd say that's the car's responsibility.

It’s about the weight of the vehicle; aggressive driving just makes it even worse.

EVs are generally quite heavier compared to similar class of ICE vehicles.


My EV runs through tires way faster than my gas car.

I, too, have a lead foot. EVs are quick, and tires are the price.

There’s quick ICE cars too, but they don’t weigh as much as the 100 or so kWh battery pack in EVs

Typical EVs are about 10-15% heavier than the comparable ICE. Yes it makes a difference, but only marginally. Normal drivers without a lead foot get 10s of thousands of miles from tires, just like ICE vehicles.

Also, few EVs that are not pickups have 100 kWh batteries; more typically 60-75.


I'd love to see some of the tire wera data that Waymo has accumulated. Despite being heavier vehicles, I bet they do well on tire wear from no hard stops or starts, driving the speed limit, keeping properly inflated, and (I assume) optimizing driving to maintain momentum (e.g. not accelerating into red lights like I see so many human drivers do).

Have you experienced waymo in SF? It actually drives faster than regular folks and brakes much more harder because of that. The speed limit doesn’t apply to the streets of San Francisco and it typically accelerates to the limit as fast as possible (especially electric).

Not in SF, only in Phoenix. My rides seemed much less erratic than a typical Uber ride.

Genuinely curious if there are any real efforts to address this available to the consumer. In the kind of idiot who will buy more expensive tires because they shed less plastic, but as far as I’m aware I don’t actually have that opportunity.

Maybe I have this wrong somehow but I thought that could be categorised as "wear".

IE don't buy the tyres that last 1000[preferred units of measure], buy the tyres that last longer.

But then you could get into "performance per unit of wear" and how that is all defined is a wombat hole of discussion.


Steel wheels on a steel track don’t have this issue.

Can they make tires without these problems?

Tyres trade material for grip, so, I think it's unlikely.

Sure. They already do. We use them on bikes.

Bikes have completely different needs and are very light compared to cars. It's apples to oranges.

tire dust is behind major die offs of juvinile salmon, thete are specific toxic compounds in it, and when therevare major rain events, all the dust in the ditches gets washed into rivers and streams in high enough concentrations to kill all the fish. from memory the toxic compound is some sort of biocide put in tires, to keep them from bieng eaten by ? algea? fungus? whatever, not an important detail, but an additive that can be eliminated or replaced, $$$$$$$$

> biocide

It's an anti-oxidant, to protect tires from UV and ozone degradation.

Tire companies are in the process of switching to a different anti-oxidant.


sounds about right, I'm surprised it's so low; we should probably stop doing the other things putting microplastics into the environment since they account for 3/4.

tires are an essential part of most people's lives, and even city people who don't have cars rely heavily on wheeled vehicles. When I think about the plastics that I take out into the environment where I subject them to wear, I can't really think of anything apart from tires.


it is not necessary though that 8 tons of energy displacement moves 60 kg individuals. we should absolutely cut down on private transit

Most cars are more like a ton and a half to two tons, not eight.

But in any case, it's not clear that there is a lot of low hanging fruit in cutting down on private transit. Aside from a few outliers, most places with pretty great public transit still have a lot of private transit too. It has many use cases that public transit is unable to fill.


No, I don't think I will.

Perhaps street cars and trains could take efficiency even further, with metal wheels.

At a certain point people will revolt at that suggestion. Most people I know are not going to give up their suburban/rural acres to live in a cramped, walkable city with no space to do everything they love.

But some people will, and the easier we make alternative modes of transportation, the more people will choose them. Want to sit in traffic all day while an LRT zips by? Nobody is stopping you.

That vehicle would require a commercial license.

The lower limit in most jurisdictions in the US is 13 tons. And also, in most jurisdictions there is an exemption for vehicles used for personal recreation (e.g. you can absolutely drive a Volvo tractor to pull your enormous fifth wheel toy hauler with nothing more than a basic driver's license).

It's disappointing they don't list any sort of detailed solutions or future tech. All they do is promote taxation and mention that tire innovation can help.

Related: tire wear rate is proportional to (total weight / number of axles)^4.

https://en.m.wikipedia.org/wiki/Fourth_power_law

This has serious implications for the future of automobile development in the age of heavy batteries.


And noise pollution! Even electric cars (which are quite heavy and produced a lot of tire wear) create loud roaring at moderate to high speeds for anyone the car is passing.

It's really not that much heavier, less than double. A Model 3 and a 3 series BMW weigh about the same.

EVs have the benefit of regen breaking though, which means less break dust contributing to the pollution.

Less than a vehicle of equivalent mass, sure.

Like many efforts (effective or otherwise) to solve environmental problems, fixing this might require new tyres sold to environmentally conscious consumers initially, to prove that it can be done. Cost effectiveness comes later, paired with government regulations.

I'm assuming there are currently no tyres on the market that contain nothing that degrades into microplastics, but please correct me if I'm wrong.


Streetcars, subways and LRTs do not require new fancy tire compounds to stop releasing microplastics. Their brake pads can, though, although I imagine that regenerative braking helps somewhat.

Bicycles are so lightweight that the amount they release is negligible compared to a car.


Agreed, and I like all those forms of transport, and use some of them when I can. But I do have to drive sometimes (for a certain definition of 'have to' of course).

We're not going to win these things by saying "just don't drive". Driving less is part of the solution, but it's not going to work by itself.


I confess I am disappointed that nobody is bothering to mention paint being the leading contributer. Guessing textiles are also higher.

As someone that bikes or walks over driving, it is still frustrating how much we'd rather blame driving over anything else.


I drive a lot less working from home

I drive a lot more now. But I preferred the old city life, taking the subway to the office instead of driving around the suburbs.

Well, maybe people will stop frowning at me for wearing my wicking running shirts now.

I truly hope this encourages manufacturers to build smaller, lighter, and slower cars.

A slower car?

They already make plenty of them


Why on earth would you think that that would ever happen?

The vast majority of people would not buy those.

Depends entirely on price.

Bullshit. The top selling car in half of us states is an 80k pickup that dodges regulations because it weighs so much. People, especially men, want giant trucks at any cost. There are plenty of affordable smaller cars but those are for weakling pussies. The us has a petromasculinity problem.

I see it as less a masculinity problem and more a "common view of physics" problem. IE it's less about masculinity and more about the perception of "winning a crash".

Cars can pass all the safety standards they like but the common view is a multi-ton ladder chassis truck keeps the kids (and themselves, their loved ones, friends...) safer than the small city car (containing others). So stupidly sized trucks are desirable...

The only way out I think is regulation. Otherwise the "outsizing" will continue.


except there aren’t any affordable smaller cars anymore…

The only thing that will do that is regulation, either mandating the types of cars we can buy, or taxing the kinds of cars we don't favor.

People in the majority prefer large, powerful cars, given the choice. And those cars already cost a lot, so any strategy of price increases to discourage them will have to be significant. This is why most people in Europe drive small, economical cars. Big cars are heavily taxed, and so is the fuel they use.


I drove smaller cars in Europe simply because bigger cars don't fit in many places. I don't think it has much to do with price.

Small streets mean fewer drivers. That means your overhead demands that you charge more per customer since you have fewer of them.

All that said, smaller roads mean smaller trucks which means more trucks more often which means more tires.


Assigning blame is less interesting to me than whether there are potential avenues for an alternative that both serves as tires and avoids this micro plastics issue.



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