What are Tire Sensors?

Among the latest technology advancements designed to keep drivers safer on the road is a tire pressure monitoring system (TPMS), which relies on sensors to track the air pressure inside each tire. In 2008, a TPMS became mandatory so if your car was manufactured since then, each tire should have a direct TPMS sensor located on the wheel. These sensors are usually mounted inside the tire, and are attached to the valve stem.

What is the Role of Tire Sensors?

When you see an alert in the shape of a horse shoe come up on your dashboard with an exclamation mark, you may wonder what it means, or how it’s related to tire pressure. The monitoring system communicates directly with your electronic tire sensors to evaluate pressure and, in some systems, temperature.

The main job of tire sensors is primarily to keep you driving safely. Properly inflated tires improve handling, fuel efficiency, and tread life, while underinflated tires increase the risk of blowouts and poor braking performance. If your car was manufactured before 2008, it may be using an indirect TPMS which doesn’t use pressure sensors but instead monitors wheel speed through the Antilock Braking System (ABS). A tire with lower pressure rotates differently, and therefore the system flags this.

When you see an alert on your dashboard, it’s because the pressure has dropped below the recommended level so a warning light appears to tell you to check your tire pressure. Some advanced systems also track tire temperature, detect slow leaks, or provide real-time pressure readings for each tire. In short, tire sensors act like a built-in safety monitor, helping drivers avoid accidents, improve fuel economy, and extend the life of the tire.

What is the Standard Number of Tire Sensors?

Most passenger vehicles come equipped with four tire pressure sensors, one installed in each wheel. And if you have a full-size spare tire, this will sometimes also have one installed. Having one sensor per tire ensures accurate, real-time readings. Unlike older systems that simply compared wheel speed to estimate a pressure loss, today’s direct TPMS sensors provide precise measurements in pounds per square inch (PSI).

Can Sensors Give a False Reading?

Even though TPMS sensors are generally reliable, occasionally they can be thrown off for the following reasons:

  • Weak or dead sensor battery: Most TPMS sensors are powered by sealed batteries that last five–10 years. When they start failing, the sensor may transmit incorrect or inconsistent data.
  • Sensor damage: Corrosion, hitting a pothole, or improper tire service can damage the sensor.
  • Radio interference: Sensors transmit wirelessly. Strong interference from other electronics or aftermarket devices can sometimes disrupt the signal.
  • Temperature swings: Air contracts in cold weather and expands in heat. On chilly mornings, your tires may temporarily read “low” even though they’re fine once warmed up.
  • Improperly reset system: If new tires or sensors are installed and the TPMS isn’t reprogrammed, the system might mismatch readings or fail to recognize a sensor.
  • Tire pressure checked right after driving: Heat from driving can make the air inside expand, showing slightly higher pressure than it really is.

If you suspect you have a false reading, manually check tire pressure with a reliable gauge, (this is best done when tires are cold) and compare the reading with the manufacturer specs which are usually found in your owner’s manual. If the light keeps coming on despite correct pressure, it may be time to inspect or replace the sensors themselves.

What Happens to Sensors When You “Air Down” for Off-Roading?

During off-roading, some drivers choose to “air down”, meaning they intentionally let air out to increase the tire’s footprint and improve traction. Because the TPMS is typically calibrated for highway tire pressures, it will show a low-pressure warning. This is normal and not harmful to the sensor itself and shouldn’t be a safety concern if it’s for a temporary purpose.

However, if you go extremely low (very soft for rock crawling, for example), there’s a slight risk of sensor impact if the tire hits sharp rocks or debris, especially for sensors mounted inside the rim. While standard sensors are fairly robust, repeated impacts or tire bead separation could damage them over time.

After returning to normal highway pressures, most modern TPMS systems will automatically recalibrate and stop the low-pressure warnings. On some older vehicles, you might need to manually reset the system.

Conclusion

Most vehicles have four sensors, one on each tires and those with a full-size spare may have five. Cars that use indirect TPMS may not have physical sensors at all. Either way, tire sensors play an essential role in keeping you safe, protecting your tires, and ensuring your car performs at its best.

Wondering how often you should change your tires? Find out in our previous blog:

How Often Should You Change Your Tires?

To have informative blogs on tire information sent directly to your inbox each month, sign up for the Tire Research Newsletter by clicking the button below and entering your email!