Why Do Tires Have Hairs?

You have seen them before on brand-new tires slated for fitting on the wheels of your vehicle. They are the protrusions that stick out of a tire’s sidewall, beckoning you to either touch or remove them. With an appearance that resembles thick hair strands or stubby cat whiskers, these rubber nubs have been dubbed tire hairs and tire whiskers.

It’s also likely that you quickly forgot about them. Tire hairs tend to shrink into stumps. But do they have a proper name? And why do tires have whiskers in the first place? Is there anything these tire whiskers do for the tires and the rest of your vehicle?

What Are Tire Hairs Actually Called?

Believe it or not, tire hairs possess a formal name. They are called vent spews, a term that says a lot about the reason for their existence.

Aside from tire hairs and tire whiskers, vent spews go by other unofficial names. Some call them sprue nubs. A sprue is either a passageway through which material enters a mold or a piece that takes solid form in such a channel, giving it the same form as its container. Like the term vent spew, sprue nub describes these parts well.

Others also call them tire nibs, gate marks, and nippers.

Do Vent Spews Do Anything?

Now that you know the actual name for tire hairs, you’re probably wondering what they do–if they do anything for the tires.

First, let’s cover what many people think vent spews do. Just as you might have called them tire hairs, tire whiskers, or something else, these parts have garnered a reputation for things they might or might not do.

Do Tire Hairs Show a Tire’s Age?

You might have heard that tire hairs can show you how old a tire is. There is some truth to this. After all, vent spews usually stand out the most on new tires. They also tend to shrink or disappear over time, degraded by typical tire usage and exposure to the elements.

However, the presence or absence of tire hairs cannot give you the tire’s exact age.

Instead, search for the tire date code on the tire. This code is a set of numbers the manufacturer adds to its tires as part of the mold pattern. Among other data, they show the tire’s date of manufacture.

Look at the four numbers at the end of the code. The first pair indicates the week number, while the last two refer to the year.

Can Tire Hairs Indicate a Tire’s Condition?

Some people believe that tire hairs can provide a clue about the state of the tire. They think vent spews on the tire indicate that the part remains in good condition.

Again, there is a kernel of truth in this belief. New tires sport the most visible vent spews, while old, used, or worn-down tires usually have smaller and fewer spews.

Avoid relying on tire hairs to determine if the tire is good or bad. Instead, put the tire through a proper inspection and check-up, which includes checking its tread depth and pressure.

Do Tire Hairs Need to Be Removed or Not?

Other people recommend plucking the tire hairs out as soon as possible. They might think that the tire whiskers affect the tire’s performance, or they might not like the look of what seems like imperfections.

Contrary to this belief, you don’t need to remove vent spews. The hairs will not harm your tire. And if you carelessly cut them off, you might hit the tire itself.

If you cannot stand the sight of tire hairs, you can pluck them off the tire like their namesake hair. You can also grind them with a file or use a sharp or scissor to cut them off. Exert care while snipping the tire whiskers, or you might damage the tire.

Conversely, people might have advised you to avoid touching the tire hairs. They think removing the tire whiskers can make the tire more likely to get damaged.

While carelessly cutting off the vent spews can damage the tire, the tire hairs aren’t untouchable. Take steps to avoid hitting the rest of the tire, and you can remove the vent spews safely.

Why Do Tires Have Hairs?

The vent spews play a critical part in the tire manufacturing process. Without the vents in the mold, the tires might emerge deformed, making them useless for vehicles.

Every tire starts as a green tire, which is basically the rubber compound formed into the appropriate ring shape but lacking the markings or pattern of treads. The green tire enters a mold that bears the markings and tread patterns for the intended tire design.

Next, the machinery heats the green tire while putting it under pressure. The heated and pressurized rubber expands until it fills the mold.

As the heated green tire expands, it presses into the mold’s patterns. When the rubber cools down, it bears the tread pattern that lets the tire grip the road surface.

Unfortunately, the pressure can create air bubbles within the gap between the rubber and the mold. These bubbles can interfere with the molding, ruining the tread patterns and potentially rendering the tire useless.

Furthermore, not all of the rubber in the green tire gets used. The excess material needs a way to leave the mold. Otherwise, they can also create deformations on the tire that will ruin its performance.

Numerous tiny holes dot the surface of each tire mold. Pressurized air and rubber can leave through these vents, reducing the possibility that air bubbles appear and ruin the tire.

Not all of the extra rubber makes it out of the vents. Some material remains inside the holes and cools into hair-like shapes that stay connected to the tire. These are the vent spews, which are better known as tire hairs.

The number of vent spews varies according to the specific design and size of the tire. However, every modern tire will have tire hairs since their manufacturing process follows the same approach.