New tyres have 8mm , scrap tyres have 1.6mm ,why aren't we driving on rubber roads , peeling strips of rubber off our kids when they walk to school ,if most cars get through a set of tyres in 2 years where does that 6.4mm of rubber go
Into your lungs, some of the particles are nano-sized so deep into the lung lining where the lungs can't deal with them, sometimes through into the bloodstream. Research is at early stages, but everything is pointing to nano particulates being much more toxic than those your lungs trap and get rid of. Modern diesels and petrols are creating these tiny particles, older ones much less so.
Otherwise, they lie around then are washed into rivers, lakes and the sea where they create havoc with fish and all the other living things we eat. Would you like a fish with cancer, Sir, or one which should be male which isn't? It's why those tiny plastic beads are being banned from cosmetic products, but obviously nothing's going to be done about vehicle tyres.
It's been shown that non-exhaust emissions (tyres, clutches, brakes) represent more than half of all road vehicle emissions and as exhausts grow ever cleaner within a decade are likely to be at around or over 80%.
Compared with by-products of fuel burning, tyre particulate emissions are bloody awful. And another reason Teslas are hugely polluting.