Eli5 why can’t tires be melted down and reused?
In: 808
Tires don’t melt. They’re made of vulcanized rubber, which is a ‘thermosetting’ material—it permanently solidifies when it’s exposed to heat & pressure. This is different from thermoplastic materials, which melt under heat and solidify when cool.
They can be shredded and used in road surfacing
https://newatlas.com/environment/recycled-tires-road-asphalt-uv-damage/
They can be retreaded although I think this is only done for truck tires. The remaining old tread is removed and the inflated tire is trued on a big ass lathe. Then a thin layer of uncured rubber is placed between old tire and new tread and the heat and pressure are reapplied. I think I learned this on a How it’s Made episode.
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Modern tires have to be able to withstand high heat from friction. Therefore, they use “vulcanized” rubber–a process invented by Goodyear long ago that changes the chemical makeup of the rubber. Vulcanized rubber cannot simply be easily melted down as regular rubber can.