An Introduction to Valve Stems and How They Work

Tires consist of more than just metal-lined rubber. Whether your vehicle is equipped with winter or all-season tires, they will feature valve stems as well. All automotive tires have a valve stem. What are valve stems exactly, and how do they work?

What Are Valve Stems?

Valve stems are tubes that connect the inside of a tire to the outer sidewall. Even if you're unfamiliar with them, you've probably seen and used valve stems before. They allow you to inflate and deflate tires. You can pump air into ta tire through the tire's valve stem. Alternatively, you can release air from a tire through the tire's valve stem. The valve stem acts as a passage from the inside of a tire to the outer sidewall.

How Valve Stems Work

Valve stems leverage a spring to control airflow into and out of tires. There are several different types of valve stems, some of which include snap-in, clamp-in and high-pressure. Regardless, they all feature a spring.

The spring is designed to prevent air from leaking out of the tire. Tires, of course, are pressurized. Even when exposed to pressurized air, the spring will remain intact while preventing leaks. Valve stem springs, however, will allow air to enter the tire.

You can inflate a tire by connecting an air compressor nozzle to it. As long as the nozzle has a pin to push down the spring within the valve stem, air will flow past the spring and into the tire. All valve stems have a spring, which you can see by removing the cap. Pressing the spring down will break the seal, allowing you to inflate the tire. And you can deflate the tire by manually pressing the spring down.

Signs of Valve Stem Failure

You should inspect your vehicle's valve stems on a regular basis. Valve stems can fail. They can become loose, for instance, in which case air can leak out of the surrounding sidewall. The spring within a valve stem may also malfunction. Over time, the spring may become stuck partially open. An open spring means that air will constantly leak out of the tire.

Valve stems are replaceable. You typically don't need to replace the whole tire. Assuming it's just the valve stem that's bad, you can replace it. Valve stems are inexpensive. Most of them cost about $10 to $15. As long as you have a valve changing tool, you can pull out the old valve stem and replace it with a new one.