Eli5 why can’t tires be melted down and reused?
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The rubber in tyres is vulcanised or cooked so it changes in a way that is not reversable. It’s a bit like baking a cake. The end product is nothing like before heating. You could grind some up and add some to new mixes but the results could never use up the quantity humans use.
ELI5 version: vulcanisation of rubber is a one way chemical process.
However, Tyre manufacturing is an awesome industry and it’s really interesting, so to give a bit more than an ELI5 version.
Modern tyres are made out of a bunch of smaller components, from silica to natural rubber to synthetic rubber to different rubbers from different regions. Modern tyres can have 100s of individual components just in the rubber compound alone.
Rubber undergoes a process when heated called vulcanisation which changes it from its natural liquid state too the rubber you know today in balls and tyres and toys.
That vulcanisation process combines all of the ingredients together and cooks them like a big cake, and the process is non reversible.
Big tyre manufacturers today like Michelin are working on making their tyres as recyclable as possible, with their new line of Pilot sport 5 tyres being approximately 20% recoverable or recycle-able components, and a goal that by 2050 all of their tyres will be 100% either recycled or recoverable or recycle-able.
At the moment the main things that can be recovered are the oils and some of the synthetic components.
[this video from Michelin](https://youtu.be/Drk0o9FIAhQ) shows the process and the difficulty in much more depth. It’s fascinating stuff.
Long term though the real plan will be for tyres to be non-pneumatic (no air in them) and 3D printable [here is a video from 6 years ago showing this concept in action](https://youtu.be/Tyc4Apyk2Rc)
The idea then would be that your tyre shop prints your tyre, and as you run through it, they simply print new layers onto it.
While you still lose some components to heat and friction, the majority of tyre waste is the carcass, which these revolutionary new designs hopes to fix.
In the truck world we allready have regroove and retread which lets one carcass live 5-10x it’s normal lifespan, dramatically reducing environmental impact and improving longevity.
Unfortunately due to consumer perceptions around retreading and car manufacturers wanting lower and lower profile tyres, regrooving and retreading passenger tyres will likely never happen.
(I work in the tyre industry, and no, I am not fun at parties unless you like manufacturing)
If they could we wouldn’t have things like “Kuwait giant tire graveyard” that keeps on getting on fire and releasing toxic fumes from time to time.
You check out what PRTI is doing. The are deconstructing tires so they don’t just end up in a landfill. https://www.prtitech.com
Why can’t you melt grandma and make a baby with it?
I’ve always wondered why they can’t be reduced to small aggregate and used in concrete for roads.
r/tiresaretheenemy would like a word. There’ll be noreanimating of dead enemy soldiers please.
Imagine trying to recycle a boiled egg so that it was runny again and could be used to make an omelette.
There are two overarching types of polymers: thermoplastics and thermosets
You can think of polymers in general like molecular ropes. In thermoplastics, those ropes aren’t tied to each other and can move past one another (melt). Thermosets are like if you tied all those ropes together in a big net. Those ropes can’t move past each other, and so thermosets cannot melt.
Tires are a thermoset material, so they cannot melt.
A lot of tires are recycled and given to high temperature kilns as fuel. For example, company I worked at used them to fuel their kiln to make cement.
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