The research from Yale University in the US the "acute toxicity" of tyre rubber is more harmful to the environment than diesel and petrol emissions.
What's also interesting is that the tire emissions from EVs are higher than petrol cars, because they weight more and have a high torque compared to traditional internal combustion engine-powered vehicles.
A couple of links to share:
It makes for interesting reading. And goes to show it's not easy finding the answer to 'clean' transport is it?