What happens to all the rubber from tires as they wear out?

Question

There must be millions of tires made and they all wear down.
So there must be tons of rubber particles along side roads.
Where is it all? What happens to it? Does it become dust?
Do we breath it?Why can't we see all those tons of accumulated particles?

Answer 1

Part of it forms a film on the road surface, along with leaked oil, brake fluid, transmission fluid, antifreeze, and so on. During the first rain of a season, this film becomes very slick, and lots of accidents result. Yes, much becomes dust, and yes, we do breathe it. We do see it. Wash a car and then leave it parked for a few days near a busy road. Much of what you find will be particulate matter from the exhaust of unregulated diesel engines. A good, modern auto tire will lose half an inch of tread in 40,000 miles of travel. That's still small, compared to the other sources of dust and air pollution.