TPMS – Tire Pressure Monitor System

Jan 6, 2023

Tire Pressure Monitoring Systems (“TPMS”) are integrated assemblies that include sensors in the tire stems, and they exist for the purpose of warning a driver when the air pressure in any of their tires has dropped to an unsafe level.

The U.S. Congress passed the Tire Recall Enhancement, Accountability, and Documentation (TREAD) Act of 2000. Among other things, the act mandated that all passenger vehicles weighing under 10,000 pounds sold in the U.S. as of September 1, 2007 be equipped with a Tire Pressure Monitoring System that warns drivers if any of the tires on the vehicle are underinflated by 25% or more (a phase-in began in 2005). Unlike in the United States, TPMS sensors are not mandatory in Canada. That being said, disabling a TPMS system by not installing sensors can potentially put a tire vendor into a liability situation should an accident occur because of underinflation.

Using a set of winter rims without TPMS sensors will typically not cause any other on-board system to malfunction as the TPMS system runs independently. You will just have to live with the warning indicator on the dash.

TPMS sensor and valve

Direct / Indirect TPMS

Direct TPMS uses a wheel-mounted sensor to measure the air pressure in each tire. The sensor then transmits the information to the car’s computer system, triggering the dashboard indicator light if the air pressure drops to 25 percent below the recommended tire pressure. Some vehicles with direct TPMS will indicate individual pressures for each tire.

Indirect TPMS uses anti-lock braking system wheel speed sensors to compare relative wheel speeds. When a tire is low on air, the circumference of the tire will be smaller, which can cause the tire to roll at a faster rate than the other tires on the car. If this happens, it will trigger your indicator on your dashboard, letting you know a tire is low on pressure. The indirect system is less sensitive than direct TPMS and does not indicate tire pressure and position.

TPMS Advantage

The TPMS eliminates guesswork by notifying you if a vehicle is low on air. This knowledge can not only help prevent accidents but can also help you improve your gas mileage, improve wear and allow for tire repair before running flat.

Direct TPMS can be used to set tire pressures more accurately to improve tire life. Using the TPMS to check pressures and deflating until all 4 tires have the correct pressure will ensure maximum wear and performance of your tires.

It’s important to remember that even though there are many benefits to having a TPMS, it’s not an omnipotent piece of machinery. Although a direct TPMS system notifies you when the air pressure in your tires drops 25 percent below the recommended pressure, you should still check your tires regularly so that you can detect low pressure before it reaches this significant threshold.

TPMS Display
TPMS Warning Light


Your TPMS can also warn you about existing or impending problems with your vehicle. When the indicator warning light flashes on and then off, then remains illuminated, your vehicle is warning you that the TPMS is malfunctioning and is no longer monitoring your tires. If this occurs, you should take your vehicle in to be looked at immediately.

Also, when your TPMS signals that you have low air pressure, it doesn’t tell you the cause. If the light continually comes on and off, it’s important that you take your vehicle to a tire or auto shop to make sure that there’s nothing seriously wrong with your tires.

In summary, a TPMS is an essential system in your vehicle. It doesn’t solve every problem, but it is considered to be the most important safety system in your car or truck, aside from the seatbelt. Knowing that a system is monitoring your tire pressure not only provides a sense of security but also gives confidence that drivers will make it to their destination without any mishaps.

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