All passenger vehicles manufactured since 2006 are equipped with tire pressure monitoring systems, also known as TPMS. This feature is designed to alert you when your tires aren’t properly inflated by displaying a warning light that looks like the cross-section of a tire with an exclamation point inside of it. In some vehicles, the TPMS may also create a digital readout that shows the psi (pounds per square inch) of air in each tire.

How Does the TPMS Work?

There are two different types of tire pressure monitoring systems: direct and indirect. With a direct TPMS, the tire pressure is monitored by sensors located in each wheel, in either the valve stem or the wheel hub. The TPMS measures the air pressure and sends it to the central control unit. The central control unit then reports the data to the vehicle’s information system. 

Indirect TPMS measures the air pressure using software, rather than physical sensors. Although the TPMS may utilize other sensors in the vehicle, like the accelerometers or wheel speed sensors, indirect TPMS primarily uses the anti-lock braking system, which measures the difference in the diameter of each tire. 

Why it’s Important to Check Your Tire Pressure Manually

Although the TPMS is a great safety feature, you shouldn’t solely rely on it to let you know when you need to add air to your tires. The TPMS warning light is designed to turn on when your tire pressure is 25% lower than the manufacturer’s recommendations. Unfortunately, at this point, your tire is already severely under-inflated. 

Although it’s very handy, the TPMS is not a replacement for a tire gauge. You should still check your tire pressure manually at least once a month. You’ll find the recommended tire pressure located somewhere near the door jamb or in your owner’s manual. If you’re having trouble finding it, we’re also happy to look it up for you! The best time to check your pressure is first thing in the morning when the tires are cold. 

Other Reasons the TPMS Warning Light Can Turn On

In some climates, the outside air temperature can vary as much as 40°F in a single day; that’s enough to change the air pressure by 4 psi. In some cases, that could cause the TPMS warning light to turn on, depending on the starting air pressure. That’s why it’s always a good idea to check the pressure in your tires using a tire gauge, especially if there’s a large temperature fluctuation throughout the day. 

The TPMS warning light will also turn on if there’s an issue with the system itself, like a dead sensor battery or a damaged sensor. The TPMS will also need to be reset when you get new tires or have your tires rotated. 

Why is Tire Pressure Important?

Tire pressure is important for your safety for several reasons:

• Your vehicle won’t handle properly with low tire pressure
• Low pressure contributes to friction and greater wear on your tires, which can lead to blowouts
• At high speeds, a rapidly deflating tire can cause a loss of vehicle control
• Over-inflated tires can cause uncomfortable rides and uneven tire wear

A major automotive study found that 1 in 4 cars and 1 in 3 light trucks has at least one significantly under-inflated tire. Keeping your tires properly inflated is one of the best ways to stay safe on the road—and reduce the cost of purchasing new tires! 

For questions on tire pressure or to schedule tire services, contact EuroCar Service. We specialize in all European makes, including Audi, BMW, Land Rover, Mercedes, Mini Cooper, Saab, Volkswagen, Volvo, Smart Car, Fiat, and Jaguar. Schedule an appointment today by calling 206-527-8828. 

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