A tire pressure monitoring system (TPMS) is an electronic system designed to monitor the air pressure inside the pneumatic tires on various types of vehicles. TPMS report real-time tire pressure information to the driver of the vehicle, either via a gauge, a pictogram display, or a simple low-pressure warning light.
TPMS are important safety features which can help drivers avoid dangerous tire blowouts and maintain optimal tire pressure for improved fuel economy and tire life. Read on to learn more about how TPMS work, why proper tire pressure is important, and the benefits of TPMS technology.
What is TPMS?
TPMS stands for Tire Pressure Monitoring System. It is an electronic system designed to monitor the air pressure inside pneumatic tires on various types of vehicles. The system operates by measuring air pressures in the tires and reporting it in real time to the driver.
Most TPMS use pressure sensors attached to each tire’s valve stem. The sensors transmit pressure readings to a central computer. The computer then alerts the driver if pressure falls below the optimal level. This warning comes via a low tire pressure warning light on the dashboard or a pictogram display showing each tire’s pressure.
Modern TPMS have been implemented in most vehicles since around 2007 when it became a mandatory safety requirement in the United States. Now standard in most new cars, trucks, SUVs, and other light passenger vehicles, TPMS help promote road safety and fuel efficiency.
How Does TPMS Work?
TPMS works by constantly monitoring air pressure levels inside the tires using tire pressure sensors. There are two main types of sensor technologies used: direct and indirect.
Direct TPMS utilize a pressure-sensing device located inside each wheel. This sensor monitors and transmits precise pressure readings from the tire to the TPMS control module via a radio frequency transmitter.
Indirect TPMS do not use physical pressure sensors. Instead, indirect systems rely on ABS wheel speed sensors to detect under-inflation. Since an under-inflated tire has a slightly smaller diameter, this causes the wheel to rotate faster than other tires. The system interprets this speed variance as a possible loss of pressure.
Both approaches have pros and cons, but provide generally reliable pressure readings to help drivers maintain proper inflation. The onboard control module receives the tire pressure data and uses dashboard warning lights and displays to alert drivers of any issues.
Most TPMS also feature replaceable lithium batteries with automated low-battery warnings. This alerts drivers when the sensors need new batteries, ensuring the system keeps working properly.
Importance of Proper Tire Pressure
Maintaining correct tire pressure is important for a number of reasons:
- Prevents blowouts – Under-inflated tires can overheat and experience catastrophic failure from excessive sidewall flexing. TPMS helps prevent blowouts.
- Improves handling – Under-inflated tires have a smaller tire contact patch which reduces grip, steering precision, and handling.
- Reduces tread wear – Low pressures cause tires to wear unevenly and rapidly. This significantly shortens their lifespan.
- Saves fuel – Under-inflated tires have higher rolling resistance which makes the engine work harder, wasting fuel.
- Prolongs tire life – TPMS keeps pressures optimized to distribute wear evenly across the tread, increasing tire longevity.
The optimal tire pressure varies based on tire type, vehicle weight, and other factors. TPMS systems are typically calibrated to the vehicle manufacturer’s recommended pressures for the specific tires installed. Drivers should ensure pressures match the sticker inside the door jamb or vehicle owner’s manual.
Benefits of TPMS
Here are some of the major benefits provided by tire pressure monitoring systems:
Prevents Blowouts – Sudden air loss can cause drivers to lose control. TPMS helps eliminate blowouts, enhancing safety.
Improves Fuel Economy – Under-inflated tires waste fuel. TPMS keeps pressures optimized for gas mileage. Savings of up to 3% are possible.
Extends Tire Life – Most tires wear out prematurely from under-inflation. TPMS allows tires to last for their full mileage.
Provides Early Leak Warnings – TPMS spots slow leaks and pressure loss so tires can be repaired. This prevents damage from driving on a flat tire.
Reduces Maintenance Costs – By preventing damage from under-inflation, TPMS saves on tire replacement and repairs.
Enhances Driving Performance – Proper inflation provides better braking, acceleration, steering, and cornering.
Promotes Even Tread Wear – Consistent pressures allow tires to wear evenly and get the most life possible.
Gives Peace of Mind – Drivers no longer need to check pressures manually. TPMS offers set-it-and-forget-it monitoring.
TPMS Warning Lights
TPMS use dashboard warning lights to alert drivers of tire pressure issues. Warning lights may also signify faults with the TPMS system itself. Here are the most common TPMS warning lights:
- Low Tire Pressure – This yellow or amber icon indicates that pressure is low in one or more tires. It typically shows a pictogram of the tire location(s) affected. Drivers should pull over and fill the tire(s) to the recommended pressure level.
- TPMS Malfunction – This light indicates a malfunction with the TPMS system itself, not the tire pressures. Potential causes include failed sensors or other electrical faults. The light may stay on solid or flash intermittently. The vehicle should be serviced to diagnose and repair the problem.
- TPMS Reset – After rotating tires or adjusting pressures, the TPMS system must relearn the new sensor positions/pressures. This light reminds the driver to reset the TPMS using the designated reset procedure. Consult the vehicle owner’s manual on how to perform the reset.
- TPMS Low Battery – If the TPMS sensors have integrated batteries, this light indicates one or more of the batteries need replacement. The low batteries should be changed so the sensors keep transmitting tire data.
Knowing these warning light indicators helps drivers understand what the TPMS system is communicating. Promptly addressing problems enhances safety and performance.
Direct vs. Indirect TPMS
There are two types of TPMS systems in use today: direct and indirect. Here is an overview:
- Uses physical tire pressure sensors attached to each wheel
- Sensors measure actual tire pressure and transmit readings to the TPMS control module
- Provides the most accurate pressure measurements
- Requires batteries to be replaced periodically in the sensors
- More expensive since sensors must be installed on every wheel
- Uses the ABS wheel speed sensors to detect under-inflation
- Measures pressure indirectly based on relative wheel speed
- No physical tire pressure sensors to maintain
- Not as precise at reporting exact pressure values
- Cannot reveal which specific tire is under-inflated
- Typically less expensive than direct TPMS
Both approaches have their merits and meet all regulatory requirements. Direct TPMS offers more precision but requires sensor maintenance. Indirect TPMS is lower-cost but uses inference to estimate pressures. Overall, both successfully warn drivers of low inflation before it becomes dangerous.
To keep a TPMS operating properly, periodic maintenance is required:
- Reset after tire rotations – TPMS must relearn the new tire sensor positions after rotating or changing tires. Follow the vehicle owner’s manual reset procedure.
- Check sensor batteries – Replace the sensor batteries as needed when the TPMS low battery warning light comes on. Use the correct replacement battery type.
- Inspect sensors – Look for external sensor damage like cracked/missing valve caps. Replace damaged sensors.
- Check sensor torque – The sensors must be properly torqued on the valve stem to avoid air leaks. Tighten to spec if loose.
- Update sensor IDs – TPMS sensors are coded with identification numbers. Any new replacement sensors must be reprogrammed to match the vehicle.
- Recalibrate for new tires – The system may need a recalibration when switching to new tires of a significantly different size.
Proper TPMS maintenance ensures you get the maximum benefit and warning protection from the system. Consider having your tire shop or mechanic handle any needed sensor-related services.
Frequently Asked Questions (FAQ’s)
How do I tell if I have TPMS on my vehicle?
Look for a low tire pressure warning light on the dashboard that looks like a horseshoe shape or exclamation point inside a tire pictogram. This indicates your vehicle has TPMS. You may also see separate reset or malfunction indicator lights related to TPMS.
What is the correct tire pressure?
Consult your vehicle owner’s manual or door jamb sticker for the recommended inflation pressure for your specific tires. Do not exceed the maximum pressure listed. TPMS sensors are tuned for your vehicle’s pressures.
How do I reset the TPMS after adding air or rotating tires?
A TPMS reset relearns the sensor positions and pressure baselines. Follow the reset procedure in the vehicle’s owner manual, which typically involves pressing a button or sequence of buttons. New sensor ID’s may also need to be programmed.
Why does the light stay on after I fill the tires?
It can take a few minutes of driving for the TPMS to recheck pressures and turn off the warning light after refilling tires. If the light stays on, you may need to perform the system reset procedure.
Do I have to replace all 4 TPMS sensors if one fails?
No, as long as the other 3 are still functioning properly, only the failed sensor needs replacement. The new sensor must be programmed to the vehicle.
How long do TPMS sensor batteries last?
Around 5-7 years on average. The vehicle will provide a low sensor battery warning light when they need replacement. Use the correct replacement battery type.
Can I disable TPMS temporarily?
TPMS should not be disabled except briefly for off-road use to avoid constant false warnings. Driving extended miles with TPMS disabled is not recommended or legal.
In summary, a tire pressure monitoring system is an important safety feature that every driver should understand and maintain. TPMS provides continuous monitoring of tire inflation to prevent blowouts, enhance handling, maximize fuel economy, and extend tire life. By illuminating dashboard warning lights at the first sign of pressure loss, TPMS protects you and your passengers against the dangers of under-inflated tires. Performing the basic maintenance steps detailed in this article will keep your TPMS working properly for maximum benefit over the life of your vehicle.
Proper tire inflation is a vital part of vehicle safety and performance. TPMS technology makes it easy for drivers to maintain optimal pressure without the need for manual tire checks. These electronic monitoring systems enhance road safety, handling, fuel economy and tire longevity.
TPMS works round the clock to provide advanced warning against under-inflation. By reacting quickly to low pressures, blowouts and flats can be avoided. Tire sensor batteries and overall TPMS maintenance is straightforward. Understanding the various warning lights ensures drivers recognize issues right away.
Overall, TPMS offers invaluable benefits and peace of mind for drivers. These integrated electronic systems have become required standard equipment in new vehicles for good reason. Drivers can be confident in the road safety and performance of their vehicle knowing TPMS is on the job, monitoring tire pressures at all times.