ELI5 What is the purpose of the little individual hairs on tires?

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Absolutely nothing. They are just manafacturing artefacts, either injection ports, or air escape ports, rubber stays behind when the tire is removed from the mold. They do no harm, they usually wear out after a few miles, and everyone’s happy. Manafacturer didn’t waste time/manpower to remove something that’s completely irrelevant, and the customer gets an indicator that the tire is brand new. EDIT: Thanks for the rewards and the upvotes. To add some more info from people who actually work in tire industry down below: these are air vents, so that when the tire is shaped against the mould, air can escape, and due to pressure some rubber starts pushing out also. This is not universal to all tires, some use a different mould that does not leave these artefacts.

himmelstrider

They don’t have a purpose, they are just leftovers from the manufacturing process. As rubber is injected into a mold, there are vent holes that allow air to escape, so no bubbles end up within the tire and weaken it. A little bit of rubber goes out these holes as well, producing the hairs you see on the tire.

Lamp11

This has been adequately answered several times but I wanted to add that they’re called “sprues.”

EitSanHurdm

As some mentioned, they don’t really serve a purpose, however, I’ll be damned if they are not a good indicator to show that the tire is new

justadudenameddave

oh cool. my parents had told me it was so you could tell if the tires were actually new or if you were being lied to by a salesperson.

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