Tires seem to be completly another beast. Apparently, most of the pollution from tires are usually stuck to the roads and are washed periodically with water and soap [1]. I am not sure how much tires contribute to air pollution.

https://nmbu.brage.unit.no/nmbu-xmlui/bitstream/handle/11250...

Sounds like it's more so water pollution where tires are bad:

> Driving is not just an air pollution and climate change problem — turns out, it just might be the largest contributor of microplastics in California coastal waters. [...] Rainfall washes more than 7 trillion pieces of microplastics, much of it tire particles left behind on streets, into San Francisco Bay each year — an amount 300 times greater than what comes from microfibers washing off polyester clothes, microbeads from beauty products and the many other plastics washing down our sinks and sewers.

https://www.latimes.com/environment/story/2019-10-02/califor...

Interesting:

"Rubber is also considered plastic, both natural (isoprene) and synthetic (styrene butadiene)."