Perhaps you misread. The microplastics in the ocean are from airborne tire particles, as in from cars' tires rubbing on roads, that get washed away into the oce

Perhaps you misread. The microplastics in the ocean are from airborne tire particles, as in from cars' tires rubbing on roads, that get washed away into the ocean. You could build cities of tires in the ocean and they would probably not be significant compared with normal tire friction in normal vehicle use. Also most of those reefs will be covered by debris and ocean flora, synthetic rubber is mostly decomposed by friction or UV radiation if it's left alone and covered in ocean stuff it will arguably be insignificant compared to your personal contribution of eroding tires on your way to work.