It’s part of the problem, but I don’t think we’ve studied individual contributors as much as looked at the big picture. There was a study on plastics in general that has some citations of the statistics it gathers, and I ran across it in looking up specifically the rubber from tires, aka tire dust from wear and tear (which all vehicles have to some degree, even EVs, and is often a part of the argument of less cars rather than different cars). So about 1 millions tons of the annual contribution to plastics in the ocean is due to tire dust in runoff waters. Also keep in mind that like many large studies that take a while to put together, I think a lot of these statistics are old (around 2016). It’s probably worse now.

I don’t know about the disposal of rubber, but the production of rubber has historically enslaved and destroyed entire populations and environmentally wrecked whole regions of the earth in Africa and South America…

Dust from tires.

There was an air-quality researcher who tried getting samples in Toronto, of pollen.

He couldn’t find the pollen.

Only tires-particles.

The significance of the changes in tires, since the 1970’s, is astonishing.

What tires can do, nowadays, … outright unbelievable, compared with way back when.

Look at how far over modern bicycle-racers can lean, compared with images of the old races, when their tires hadn’t anywhere near the grip they’ve got now…

but they’re still being poured into the atmosphere at stunning rate…

All the wear of your tires, as the tread gets thinner, its going into the ecology, either the air or the waters or the land around the roads,

& then you’ve got the oceans-of-used-tires which often can’t be recycled, or cost too much to be recycled…

There has been extensive study on this stuff, btw, dig a bit & you’ll find some in-depth stuff!