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Comment by arthurbrown | Hacker News Reader

Electric cars don't reduce emissions from tyre and brake wear. These particles make up a huge amount of air pollution at a size small enough to cause health issues. Once they settle, they are swept into waterways and form the majority of our microplastic problem.

https://www.sciencedirect.com/science/article/pii/S135223101...

https://www.theguardian.com/environment/2018/nov/22/tyres-an...

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Regenerative braking certainly is reduced by EV's; a Tesla may never replace its brakes during its lifetime. Reading the paper, the dominant source of PM2.5/PM10 is resuspension of dust already on the road, rather than tires or brakes.

> a Tesla may never replace its brakes during its lifetime.

If you live in a northern area where they salt the roads you will need to reduce regen or perhaps occasionally do an emergency stop to grind the corrosion off the brake disks in the winter.

I had to have two brake disks replaced at the last service on my 2015 S 70D because they were too rusty.

But generally speaking you are correct.

What's the dominant source of dust on the road? Would expect a large amount of that to be tire/brake wear.

Brakes on Tesla are said to last twice as long or more. That would be a direct reduction in brake dust. Even with my Model 3 being floored from every stoplight since I’ve bought it, I’ve yet to hear the tires chirp. Suspect the tire wear is less than a comparable gas car due to the better traction control, and the harder tread in pursuit of lower rolling resistance.

All tyres are in a state of slip when you are accelerating or braking, it's unavoidable.

Isn’t the purpose of traction control to keep the tires in contact with the ground in a static coefficient of friction, and thus not slipping?

If there was zero slippage there would be zero acceleration.

My understanding is that tires, even when accelerating, can operate in the static coefficient of friction range. And, you want them to operate in the range, because it provides the greatest acceleration. But, maybe my mental model is wrong. The following video is from someone who has considered it much more in depth.

https://youtu.be/iyeLXkacocA

That is a "driver's view" of tire slip (for best results, don't spin or slide the tires too much) rather than a chassis or tire engineer's view of tire slip (if you don't slip the tires, you can't generate any force).

Not quite right? The tires have strain, but they do not have to slip on the surface.

That's not very intuitive. Can you provide a longer explanation for this?

Here's a pretty decent, graspable explanation: https://physics.stackexchange.com/questions/142463/does-a-ti...

Tires that are not slipping are not creating any force against the road surface (so they don't have to slip when coasting, but will slip while accelerating longitudinally [braking or accelerating fore/aft] or laterally [cornering]).

Would you say that a rubber belt on a pulley is slipping? I’m sure at a microscopic level there are some places where the belt isn’t making perfect contact and the rubber is slipping across the pulley, but at a macro level, the belt remains in contact with the pulley in the same place from when it initially contacts until it disconnects.

https://youtu.be/ZVW9uMeFXK8

Yet another video about static coefficient of friction on tires that aren’t slipping. Electric cars are more easily able to keep their tires in this maximum static coefficient of friction range, maximizing acceleration.

At a micro level, I would say that a rubber V-belt on a pulley which is transferring significant force is slipping as an unavoidable element of delivering that force.

What traction control/ABS does is keep the the tire slip ratio in the right range to optimize acceleration. https://www.researchgate.net/figure/Typical-tire-longitudina...

What we intuit about whether or not we're slipping our tires every time we brake for and then drive away from a traffic light "without slipping them" is not actually correct at a micro level. With respect to this thread, it is the micro level that is relevant to tire wear and resulting particulate emissions from that slippage.

Well that and the regenerative braking.

What is the relevance to the article? I skim read it, was there a part to do with tyre wear I missed?

It's great that they're getting reductions of this magnitude for watercraft, this should absolutely continue.

But it is damning for electric cars. The tailpipe emissions (measured in this article) that are reduced by going electric are marginal in comparison, and the other emissions are still entirely present.

It doesn't seem damning, electric cars are a not a silver bullet. This seems like an additional problem to tackle concurrently.

If we came up with a new "Environmentally Friendly" tyre that solved that problem, than we would still have exhaust emissions to deal with. You don't need to fix both to attempt to improve one.

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