What is a Tire Valve Stem?

A tire valve stem is a physical pathway for air to enter and exit a tire.

Your car’s tires are filled with air at a high pressure so they can maintain their shape while still being pliable while driving. Filling up your tire with air and maintaining the correct tire pressure is important for the health of your tires and your own safety while on the road. A key component of filling up your tire is the tire valve stem. 

Where do you find tire valve stems? What does a tire valve stem do? What are the different types of tire valve stems? 

In this article, we’ll explain the three main types of tire valve stems, why the tire valve stem is important, and how to tell if your tire valve stem is broken. 

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What Does a Tire Valve Stem Do?

When you fill your tire, the valve stem is the part that sticks out of your tire that serves as the exit or entry point for air. They contain a one-way mechanism (typically fitted with a pin), to prevent air from escaping while filling. If you’ve ever filled a bicycle with air, you’ve seen a similar valve stem mechanism. The difference is that a car tire’s valve stem is meant to handle much higher air pressure than bicycles, and modern versions may be equipped with a tire pressure monitoring system.

Tubed tires vs tubeless tires: Tires with tubes have valve stems attached to the inner tube of the tire — not the tread of the tire. Tubeless tires have valve stems mounted directly on wheel rims. 

A tire valve stem is where you fill your tire with air. Additionally, it ensures that your tire is maintaining the correct air pressure. If you have tubed tires replaced, you won’t always get a new tube! That means that you can reuse valve stems.

A tire valve stem is made up of: 

• The cap
• A core (with the pin that’s pressed down on to put air in the tire)
• The body

If you buy a new set of tires, mechanics may recommend getting new tire valve stems around the same time.

How Does a Tire Valve Stem Work?

A tire valve stem is designed to safely fill the tire with air and to ensure air doesn't leak out. The tire valve stem is located on the wheel, so it is less likely to be bumped or hit while the car is moving. 

When you take the cap off the valve stem, you’ll notice a small pin in the middle of the valve called the valve core. When this pin is pressed, air will release from the tire. If you’re filling your tire with air at a mechanic or gas station, the air compressor automatically presses the pin and pumps air into the tire. The compressor will push air into the tire, regulating airflow to prevent over inflation, and let you monitor the tire’s pressure as you fill it. 

A tire’s pressure will naturally decrease over time due to temperature changes and natural slow permeation, so regularly monitor your tires. Because of this, it’s also important to check your valve stems! A broken or damaged tire valve stem is a common reason a tire isn’t maintaining the correct tire pressure. 

Types of Tire Valve Stems

There are three broad types of tire valve stems on tires. You will probably only encounter two in your vehicle's tires.

Rubber valve stem

The most common type found on passenger vehicle tires, the rubber snap-in valve stem has a rubber body and is known for being easy to work with. If you ever have to replace your tire’s valve stem, it’s much easier to install a rubber valve stem. However, rubber valve stems are known for wearing down and cracking over time, similar to the rubber of a tire. These stems can handle air pressures up to 65psi on average, though some specialty tires can handle 80 to 100psi.  

Metal valve stem

A metal snap-in valve stem is the direct alternative to a rubber valve stem. The body is constructed with metal rather than rubber, making it far more durable. However, metal valve stems can also corrode or rust over time, especially if you’re in winter areas that have salted roads. Some are made with a nickel-plated brass, which tends to last longer. Regular maintenance prolongs the life of metal snap-on valve stems.

Metal valve stems are known for being more difficult to replace, as you can’t bend and adjust the metal as easily as rubber. These stems can also handle air pressures up to 65psi on average, although some types can handle up to 200psi.  

High-pressure valve stem

You aren’t as likely to encounter a high-pressure valve stem on a commuter vehicle tire, but you will see them on high-performance vehicles, trucks, RVs and industrial applications. A high-pressure valve stem has a clamp design where you tighten a nut on top of the valve stem to “lock in” the stem so air can’t leak out. Because of this, they’re usually brass or stainless steel, so you can securely clamp the nut over the stem so that air doesn’t leak out. These stems are designed for pressures higher than 65 psi. 

What Does a Broken Tire Valve Stem Look Like?

If you can’t fill your tire with air or are struggling to maintain tire pressure, your tire stem may be broken and need replacement.

The most common way a tire valve stem breaks is the core snapping or bending. If you can’t press the pin down to fill the tire with air, or if you notice the pin is crooked, it probably means that your tire valve stem requires replacement. 

Another common occurrence with rubber valve stems is the body snapping off the tire. Around the base of the tire valve stem, the rubber will corrode and crack over time as the valve stem is moved around and exposed to UV rays and severe weather. If this stem breaks off, you won’t be able to fill your tire. 

Do you have to replace lost tire valve caps?

If you lose the cap of your tire valve stem, it’s not the end of the world. However, we recommend getting a replacement cap to prevent the pin from being bent, corroded, or damaged. You can find these anywhere auto parts are sold, and the good news is that valve caps are fairly standard. Specialized vehicles require specialized caps; otherwise, most passenger vehicles use the same size valve cap.

Can you replace a tire valve stem?

Yes, but you’ll need to deflate the tire completely to access the inner tube, which is separate from the tread. If you buy a new set of tires, you may need to get new tire stems, depending on whether you have tubed or tubeless tires. A tire valve stem isn’t easy to replace yourself, though. Depending on the type of tire, you may have to deflate your vehicle’s tires and remove them from the wheel, and fit the new tire valve stem so that the TPMS is functioning correctly -- best left to tire professionals.

When you have a new set of tires mounted on your car, ask your mechanic about valve stems. Do they need to be replaced? When purchasing a new set of tires through Tire Agent, we will connect you with a verified tire installer that can help you get a new set of tire valve stems!

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