How do tyre pressure sensors work

The next two digits represent the size of the wheel rim that the tyre can be fitted to. It is also the diameter of the tyre from bead to bead. So a tyre marked 16 will fit on a inch wheel rim. The speed rating of a tyre is represented by a letter of the alphabet at the end of the tyre size code and indicates the maximum speed capability of the tyre.

Tyres receive a speed rating based on a series of tests which measure the tyres capability to handle a set speed for a prolonged period of time.

If you are unsure what speed rating you need, be sure to check your vehicle handbook. Choosing a lower speed rating than that recommended by your vehicle manufacturer could potentially invalidate your insurance.

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Home Blog. How do tyre pressure sensors work? So how do these devices work and where can you find them on your vehicle? How do car tyre pressure sensors work? The two main types of TPMS are direct and indirect. Regular signal from an indirect TPMS showing normal tyre pressure. Irregular signal from an indirect TPMS showing lower tyre pressure. Where are tyre pressure sensors?

Tags : Tyres. Like most quickly-introduced changes, there were problems with the systems. But as technology improves, and engineers refine how the systems function, they're becoming smoother and more reliable. Read on and find out how the systems actually see inside your tire, what they see, and how your car reacts to the information. Direct tire pressure monitoring systems use individual sensors inside each tire, and sometimes a full-size spare , to transmit information to a central control module.

The sensors read internal pressure, and sometimes temperature. The information received at the module is analyzed, and any issues with any of the tires are sent to the car's vehicle information system, or low-pressure light. Information is most often sent wirelessly as a radio signal. While some aftermarket systems are mounted outside the tire, most manufacturers use a sensor mounted inside the tire. This is where the expense for the consumer comes in.

Each sensor has a battery with a life of about a decade. On most, the battery is not serviceable, and the entire sensor must be changed. The sensor stem is also subject to damage, as is the sensor itself, when the tire hits a curb or the car gets into an accident. And each time a sensor is changed, it generally has to be reprogrammed into the control module so it can be recognized. The wireless system is also prone to problems and challenges, as well as being integrated with other car systems that can fail or become corrupted over time.

Added to this mix is the often-proprietary technology used by each manufacturer, making the range of sensors out there a confusing mix for shops and consumers. Do your P. They wear significantly faster and their performance is reduced. No need for a headache, just get your tires aligned! Save yourself money and be safer. Get your tires rotated! Direct sensors, though, have one more potential failure point. Over time, these go flat, and the whole sensor needs to be replaced.

And, as with replacing sensors for adaptive cruise control or automatic emergency braking, this requires a system recalibration. It reads out in pounds per square inch psi , and it illuminates an amber warning light to alert you if one or more tires are low on air.

Millions of these systems have been fitted to passenger vehicles since the model year, when they were made mandatory in the United States. Tire-pressure sensors are usually attached to the valve-stem assembly of each tire and are powered by batteries. In the event that the sensor detects that air pressure in a tire has dropped to a dangerously low level—25 percent below the recommended air pressure, according to federal government regulations—a warning message or light will display in the instrument cluster.

Inflation pressure recommendations for the tires that originally come on a car can usually be found on a label on the driver's doorsill. TPMS sensors are powered by batteries designed to last several years, but they do eventually lose their charge.

Because the sensors cannot easily be removed, when their battery dies the entire sensor must be replaced. Replacement tire sensors vary in price depending on your vehicle and can be found from many sources, from Amazon to Advance Auto Parts to Tire Rack —or at your local tire store. You can continue to drive indefinitely with a failed TPMS sensor in one or more of the wheels, but then the system will never be able to warn you if you've picked up a puncture in those tires and are on the verge of a blowout.

There is a second type of tire-pressure monitoring system, which works entirely differently. It does not employ tire-pressure sensors in the tires, relying instead on the anti-lock-braking system's wheel-speed sensors to determine if any particular tire's rotational speed is out of sync with the others.

This indicates that the suspect tire's circumference has changed and that it could have lost air pressure. To ensure that your vehicle's TPMS system's pressure sensors remain operational for as long as possible, always reaffix the valve-stem cap after checking air pressure or inflating the tires.

This helps prevent valve-stem corrosion, particularly where salt is used to clear the roads in the winter. If the TPMS warning light does illuminate—the light looks like a flat tire as viewed from behind the car—check your instrument cluster display and then use a tire-pressure gauge to check all four tires to determine which ones, if any, are low.

Fill them to the manufacturer's recommendation as soon as possible, remembering that, if you've driven several miles to get to an air hose, your tires will have warmed up and you should inflate them evenly.