In other words: sooner or later every bit of synthetic rubber that is part of the tire when it leaves the factory and that isn't part of the tire when it goes t

In other words: sooner or later every bit of synthetic rubber that is part of the tire when it leaves the factory and that isn't part of the tire when it goes to wherever those things go at EOL will eventually be washed away by rain. And then it either becomes inland sediment or make its way into the oceans.