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up vote 7 down vote favorite

Up close you can see at least three 'hairs' of rubber from this picture from the side of my tyre:

enter image description here

Why do they exist? I've heard they are just a bi-product of the manufacturing process.

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2 Answers

up vote 7 down vote accepted

They serve no purpose on the finished tire, but they are a consequence of a very important detail of the fabrication process.

While rubber is being injected in the mold, there are risk of air bubbles forming between the rubber and the mold, which can prevent the rubber from getting in all the intricate patterns of the mold, thus producing malformed tire.

That's why the mold has vent holes that allow air to get out. A little rubber gets squeezed into these holes and that is what causes these "hair".

These hairs have no useful purpose as long as riding concerns, so they can be removed with no consequences.

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up vote 12 down vote

Those are "sprues" -- bits of rubber that went into the vent holes in the tire mold. They serve no purpose.

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So I can cut them off if I like? – Ambo100 May 31 '12 at 14:58
2  
Go cut them off! Except if you want some potential buyer of your tires to be sure they are "brand new" :o) (nail cutters or scissors work best) – heltonbiker May 31 '12 at 16:42
@heltonbiker: That's a good point. The reason I ask is because I tend to pull them out when I'm bored without realising what I'm doing. – Ambo100 May 31 '12 at 16:56
just normal riding will cause them to fall off, but you can pull them off with no problems to the tire. The only thing to think about it like @heltonbiker said, it lets other people know it is a new tire. – BillyNair Jun 1 '12 at 6:04
1  
They do serve a purpose: they're new tyre indicators! – Hugo Jun 1 '12 at 14:20

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