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Why do my tyres have hairs?


Vent spews on a Toyo tyre

Those little rubber nibs actually play a vital role.

The little rubber hairs that cover tyres are a common source of mystery. Why are they there? What do they do? Are they important?

Before we get into what they are, let’s round up some myths on the odd little plastic nibs. 

  • They’re a good way to check a tyre’s age or condition (they aren’t). Here’s how to check that.
  • They need to be removed (they don’t)
  • They should never be removed (you can)
  • They are ugly (subjective opinion)

The real name for these hairs all sound mildly insulting. 

They are called ‘vent spews’, a weird name for something extremely common.

Other names include sprue nubs, tyre nibs, gate marks or nippers.

The hairs actually play a vital role in the tyre manufacturing process.

To understand why, you first need to know a thing or two about how tyres are made.

A green tyre, (that is, a tyre compound built into shape but with no markings, information or tread pattern on) it is placed into a tyre mould.

Heat and pressure is applied to the green tyre. The rubber expands to fill the mould, taking on the tread pattern and Toyo Tires Proxes or Open Country label in the process.

During the application of pressure and heat there is a risk of air bubbles forming between rubber and mould. Air bubbles prevent the mould from forming correctly.

A spew hole, or vent sprue is the tube that excess pressure escapes from as the rubber expands.

Toyo Tires technical manager Steve Burke explains why your fresh tyres have these hairs/nibs/nubs/spews.

“Air escapes, ensuring no air bubbles between tyre and mould, and takes with it little bits of the rubber. This is how vent spews are made.

“The spews on the tread face are mostly shaved off, but on the shoulders and sidewall of the tyre, spews remain intact.”

So, should you remove them?

“It really doesn’t matter. Vent spews have no functional purpose post-manufacturing. Many show car owners take great pride in shaving or clipping the nibs down,” says Steve.

“There is no practical reason to remove them, but if you must, avoid scissors and blades and just grab them with your hand and pull them off. It’s actually pretty good stress relief.”

Another mystery solved.

Get your hands on a fresh set of Toyo Tyres at a dealer near you, and get up close and personal with your very own vent spews.