[thedoc (OP)]

My question is about the rubber that is lost from the surfaces of tyres throughout the world.  All the time, every country, 24 hours a day, tyres are losing minute amounts of rubber and wearing the tyres out.  Where does it all go?  Does it turn into dust?  Does it mix in with our water systems?  Is there a big well at the bottom of the sea where it’s gathering?  Where does it go to and what does it do?
Asked by Alan, Orpington


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[thedoc (OP)]

We answered this question on the show...



Dave - If you've ever changed a bicycle tyre you’ll know where quite a lot of it ends up and that’s all over your hands, because you're covered in a horrible black gunge which I think is mostly tyre rubber.  Then what's going to happen to a kind of black powder all over the road, it’s going to get caught up by water and washed away.  I imagine that rubber is a natural thing so eventually, some of that could be broken down I’d thought biologically.
Chris -  It’s vulcanised though isn't it, because it’s got some sulphur added so it cross-links,  making it harder to breakdown as it’s been modified that way.  I think it’s quite persistent.
Dave -   Okay, it’s going to be a very slow process so I would’ve thought most of it ends up in sediments in streams and rivers, and it will slowly get fossilised in there or at the bottom of the sea, where it will sit until it’s degraded and turned maybe back into oil.
Chris -   It turns into millions of tonnes of rubber on the roads every year actually. I recently calculated how many tonnes of rubber we get through the western world every year - just some simple back of the envelope calculations: millions of tonnes of rubber get used every year and as those tyres are being replaced, you can never work out that there are millions of tonnes of rubber that are worn out onto the road surfaces.

[graham.d]

I reckon it ends up in the same place as my missing socks.