Why Do Tires Have Whiskers on Them?

Close up of a brand new tire sidewall with wire whiskers visible

If you recently went car shopping or tire shopping, you might have noticed something weird. Most new tires have tiny little whiskers on them all over the tire. What are these whiskers, why are they there, and what do they do? In this quick guide, I’ll answer these questions and more.

The whiskers are the result of the manufacturing process that creates the tire. Molten rubber is poured into a hollow mold. Air needs to escape or else the mold will be unevenly filled, the tires won’t be airtight, and there will be air bubbles trapped in the rubber. To fix all of these problems, air vents are created in the mold which allows air to escape. As it escapes, it brings a little bit of rubber with it, making the whiskers you see on a new tire.

Wait, What Whiskers?

Next time you’re at a dealership or tire store, take a look at their rack of new tires. If you look closely, you’ll find little whisker-looking whisps of rubber across the tire. They’re on the tread and sidewall and completely cover the tire.

Close up of two brand new car tires with the wire whiskers visible

They’re typically only found on brand-new tires (this will be explained later), so if you look at your old Civic’s tires, you won’t see the whiskers.

Tire whiskers are thin pieces of rubber that can go straight out or have an odd angle to them.

They’re Called Vent Spews

If you want to get technical, these “whiskers” are actually called vent spews, tire nibs, risers, sprue nubs, gate marks, or nippers — but most people either call them vent spews or tire whiskers.

Some new Michelin’s don’t have them, and that’s thanks to a proprietary manufacturing method that they won’t tell anyone. Still, there’s a good chance that if you just installed new tires, you’ll be able to spot these whiskers on them.

Why Do Tires Have Whiskers on Them?

So, why did every manufacturer decide to put these whiskers on their tires? No, it’s not because of aesthetics, it’s actually a byproduct of the manufacturing method used.

To make a rubber tire, a mold is used and hot rubber is pumped into the mold. Since these tires need to be airtight and sealed, there’s a big manufacturing challenge — how do you pump in the molten rubber?

Car tire manufacturing plant with new tires on a conveyor line for production

Manufacturers will use tiny air holes all around the tire’s mold. This allows the rubber to “breathe” as it freely flows into the mold before hardening, curing, and becoming a solid piece.

As air escapes the rubber, it takes a little string of molten rubber with it. Once everything is cured, the string closes in on itself since air isn’t keeping it open anymore. This creates the whiskers.

So, the whiskers are just the result of air vents that eventually solidify into firm pieces of rubber.

What Happens Without the Air Vents?

If a tire manufacturer used the exact same method and simply removed the air holes, the tire would be a disaster. Since the air couldn’t escape, it would get trapped in the mold, creating pockets in the rubber across the tire.

These pockets are weak points. With a big enough air pocket, the tire runs the risk of blowing out as you drive.

In addition, there’s a chance the tire will lose its ability to hold air without leaking. Clearly, this means that Michelin’s whisker-free design went through a lot of engineering to get their tires to not do this.

Should You Trim the Tire Whiskers?

I just covered that as a consumer, tire whiskers don’t have any importance. So, does that mean that you should just get rid of them, or is that a bad thing?

The truth is that it really doesn’t matter. Tire whiskers have zero impact on your car’s performance, safety, or speed. In a blind test, you wouldn’t know whether the tires had whiskers or not.

Side view of a car inside a car dealership with the tire and wire whiskers visible on a chrome wheelSide view of a car inside a car dealership with the tire and wire whiskers visible on a chrome wheel

Some people hate how the whiskers look. For those people, you can either wait long enough for them all to wear out, or you can cut them away. A simple pair of scissors can be used to trim them all off, but it will wear your scissors down since there are so many.

If you choose to trim the whiskers, be careful. Since you’re assumedly handling something sharp, make sure you don’t accidentally poke a hole in your tire. That would require you to replace your tire.

For people who don’t care either way about their tire whiskers, just leave them. It’s not worth the time and energy to trim all of them away.

Some Myths About Tire Whiskers

Now that you understand what the whiskers do, I’ll talk about some of the common myths. None of these are true, and since you know why the whiskers exist on your tires, you’ll be able to dispel these myths.

They’re Used to Indicate Wear

The first myth is that these whiskers are intentionally included just to show wear. It makes sense because whiskers do wear down over time. However, a tire manufacturer would never waste time and money making tires with these whiskers just to show that the tire is new.

The better way to indicate wear is to look at the tread of the tire.

While this myth is dispelled, it’s still true that whiskers wear out as you keep driving. If you’re sold “new” tires that don’t have whiskers on the tread, I would be really skeptical.

They Reduce Noise

This myth always made me laugh. Some people say that whiskers are included so that the tires don’t make as much noise as your car drives around.

If you wonder why certain vehicles are so loud, you can rule out the tires. The engine and exhaust are typically the loudest part of a car, not the tires.

A driving car in motion moving on a road with sunset on the horizon

When tires make a lot of noise, it means that there’s something wrong. If your tires are humming, rattling, or banging, follow my guide here to fix them.

It’s also normal to hear road noise as you’re driving. This is unavoidable, no matter how many whiskers a tire has.

Plus, all the whiskers are going to be fully compressed and squished down as you drive. The weight of the car dramatically overpowers these tiny tubes.

They Prevent Scams

This myth is a little more interesting. Some people theorize that the whiskers are supposed to stop a scammer from selling you a used tire and pretending it’s brand new.

As I mentioned, these whiskers are going to wear down after you put enough miles on them. For that reason, it makes sense how this theory started — if you don’t see whiskers on a tire, you know that it’s used so you shouldn’t pay full price for it.

That definitely helps you when you buy tires from a third party. However, that’s not what the whiskers are there for. The better thing to test is the tread depth and closely inspect the tires before buying them from a stranger.

They Help the PSI Distribute Evenly

Since these little whiskers seem like they have air inside of them, people wrongfully assumed they’re there to help the pressure evenly distribute across a tire. To be honest, this myth is a little confusing to me.

Close up of a car tire and wheel on a Mitsubishi Outlander XL

The simple fact is that the air in these tiny whiskers is a small percentage of the tire’s total air. Plus, how do you explain the fact that whiskers can wear away and the tire will still work perfectly?

The whiskers definitely help the air spread out while the tire is being made, but that’s the extent of their usefulness.

You Should (Or Shouldn’t) Get Rid of Them Immediately

I’ve heard split opinions about getting rid of the whiskers. One group of people argues that you should immediately trim them for whatever reason. The opposing side says that trimming them will ruin your tires so you should avoid it forever.

Both sides are incorrect. Your car doesn’t care whether the tires have whiskers or not — it will perform exactly the same and be equally safe to drive.

If you want to trim them, go ahead. If you want to keep them, then keep them. There’s no rush to make either decision, and you’re ultimately just wasting your time if you decide to cut them off.

They’re a Tire’s “Fingerprint”

Since these whiskers are so sporadic, some people think that it’s some kind of identifier, like a fingerprint for your tire. That way, you can look at all four and somehow tell if they’re from the same set or manufacturing batch.

Brand new car tires on yellow racks at a warehouse production manufacturing tire store

This myth is very untrue. The real fingerprint of your tire is the serial number. That’s a number that can tell you everything you need to know about the manufacturing of your tire.

Whiskers might seem sporadic, but they’re basically the same if you get them from the same manufacturer. They’re determined by where the mold has air vents to let the molten rubber breathe.

Conclusion

As you just learned, these tire whiskers are a result of the manufacturing method used to mass-produce tires. There are no secret uses for the whiskers, and you can decide to trim them or just leave them alone.

If you have any other car questions, check out the rest of my site. I have plenty of content to answer your questions. I also have an expert list of car products that can make your life a little easier.

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Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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