Bear in mind that the denominator is plastic pollution. Most plastic waste does not directly pollute the environment. If it is not recycled then it goes to landfills or incineration. Not ideal, but at least the damage is contained. (The bulk of ocean plastic comes from the rivers of poor countries without proper waste management.)

The issue with tyre microplastics is that it's all but impossible to channel the waste. It's the same with synthetic fabric: just washing it creates pollution that's really hard to control.

I've seen a similar number in a lot of proper scientific sources, so this article may be bunk, but the number is correct I think.

For example this article: https://doi.org/10.1016/j.scitotenv.2024.171003 They claim 27,26% in China.

And this article: https://www.rivm.nl/bibliotheek/rapporten/2024-0106.pdf They claim 24.88% in the EU and state it's among the biggest if not the biggest contributor to microplastics.

I'm all for debunking stuff, but about a quarter seems to be the currently accepted quantity to the best of our abilities to measure.

There is a bit of confusion between the amount tyres contribute into the ocean, how much into the ocean and waterways and how much in the environment as a whole. A lot of it ends up in the soil, so it doesn't contribute to plastics in the water, but still in the environment.

This is so far from the truth.

The real reason is cars are heavier. The more weight, the more wear on the tires. You can only make a tire compound so hard before they become uncomfortable rolling chunks.

In the 70s when the fuel crisis hit, cars were very inefficient. Heavy steel and heavy engines that guzzled field. As the technology has progressed we use composite materials to make them lighter where we can. Some of these materials are more expensive than others, so you won't find them on all models. Magnesium and Carbon fiber for example. We started to make cars lighter.

Then there's features, creature comforts, etc. We started adding more and more fancy features over time. These all add up. Heavy sound deadening pads are placed all over the bare chassis. Rip up your car's carpet, underneath you'll find them. They're in the door and behind the dashboard. There's even foam in the A, B and C pillars. We figured out that we can make cars quieter. Now that we can make them quieter, let's add a lot of creature comforts. Power, heated seats and mirrors. Power windows, powered lift gates, and anything else that's powered. These require electric motors. Not sure if you've ever seen these electric motors, but these are actually quite heavy little things. A few speakers is now almost a dozen in many models. Lots of trim pieces that make the car more aesthetically pleasing add weight.

Safety is a huge factor as well. One or two airbags has turned into about a dozen. Extra beams that are used to dissipate energy around you in a crash. My car has 8 alone for just the front driver and passenger.

Got a hybrid or an EV? These absolutely demolish tires because the additional components adds a lot of weight.

Even though we got better at making composite materials and reducing weight where we could, our need for creature comforts and advancement in technology has caused the overall trend for a car's weight to go up. This information is readily available if you'd like to search the Internet.

A set of tires wear endurance has only gone up over time. But because of a car's weight, it reduces its ability. Your driving habits also greatly impact how long your tires will last. Do you have a Rivian or Tesla? Go easy on the acceleration and showing off with the spirited driving. You can make your tires last less than 10,000 mi. Do you add additional weight? How long is that additional weight being hauled around? In other words, if your trunk is full of stuff, clean it out. You're increasing fuel consumption and increasing tire wear.

What? Maybe if you compare an old hard tire with no grip to a modern soft tire with tons of grip. But a modern hard tire lasts as long or longer and has more grip in all conditions.

Planned obsolescence

also, why is it spelled that way?

British spelling of tire is tyre

Yes, though note that tire and road wear scale with the 4th power of the vehicle weight. If a person on a bicycle weighs 200 pounds and a person driving a car weighs 2000 pounds then the car is going to have roughly 10,000 times as much tire wear (and microplastic shedding) as the bike.

Now consider that people on bikes can even weigh less than 200 pounds and cars can weigh far more than 2000 pounds (I heard of a recent electric SUV that weighs 8000 pounds) and it becomes clear that bicycles are a complete non-issue, relative to cars. An 8000 pound car is equivalent to 6.25 million 160 pound bicycle + rider pairings.

Now consider the effects of 18-wheeler tractor tailors with a maximum weight upwards of 80,000 pounds. These things absolutely disintegrate their tires. If you’ve done any highway driving you’ve likely seen the shredded debris of tires on the shoulder of the road.

Edit: as an addendum I’d like to note that electric vehicles tend to weigh a lot more than ICE cars, by upwards of 1000 pounds. This is one of the reasons I’m dismayed at the rush to EVs: it’s going to accelerate the microplastic problem even as it reduces CO2.

I mean just steel on steel solves this too

You want trains because they are good for the environment.

I want trains because chugga chugga choo choo.

We are not the same.