With IGOTASTi strongly being about having active and knowledgeable members, I'm contributing back to the community, aiming to educate and explain people all about their STi. Here, we are going to explain what a tire pressure monitoring system is, what it does, how it affects your car, and the pros and cons of TPMS systems.
What is a Tire Pressure Monitoring System?
A tire pressure monitoring system is an electronic device that sits inside your wheel, and monitors a tire?s air pressure via a small transmitter built into the sensor. By federal law, all vehicles built after September 2007 are required to have the system in place. In relating this to your STi, the sensor will send off a radio frequency, alerting you via a small light on the gauge cluster. In your Subaru, the TPMS light can come on by one tire being as little as one pound (1 PSI) low, or there being a fault in the tire pressure monitoring system.
Tire Pressure Montoring System Sensor
TPMS Light On
How Does TPMS Affect My Car?
The TPMS system is required by federal law after 09/01/07 build dates, aimed at preventing tire blowouts and promoting better gas mileage. In theory, this will decrease the amount of accidents related to tire blowouts, and decreasing the amount of gas cars will use due to having underinflated tires. TPMS sensors in your Subaru weigh about the same amount as a pen, so they?re not a benefit to true weigh reduction.
That Annoying TPMS Light Always Comes On!
The TPMS light (pictured above), can come on if your tires are underinflated by 1-2PSI. Instead of removing the TPMS sensors, inflate the tires 3PSI higher than the door placard states (on a cold tire); 3PSI will not affect how the tires will wear on an OEM spec Subaru. If you have your car set up for lower, or extremely higher air pressures for specific events, the light will stay on regardless.
What Should I Do to Maintain the TPMS System?
The manufacturer that makes Subaru?s TPMS system, Schrader USA, recommends replacing the TPMS valve stem every time the tire is dismounted from the wheel. From my experience in the tire industry, whether talking to the Tire Industry Association (TIA) guys, or representatives and engineers from tire manufacturers such as Michelin, Bridgestone, and BF Goodrich, they recommend installing the new TPMS valve stem whenever you get a new set of tires, or every other seasonal exchange. The new valve stem for a TPMS system, typically called a service pack, can run anywhere from $2.50 to $5.00 from most tire vendors.
Subaru TPMS Valve Stem
Frequently Asked Questions:
Q: Can I remove the Tire Pressure Monitoring System Sensors from my car?
A: Yes, but many tire dealers and vendors hesitate to remove them, or install them on a car that should have them due to federal laws and regulations. Essentially, you?re asking them to remove a safety feature.
Q: Does having air or nitrogen in my tires affect the sensors, and can I mix the two?
A: Air as we breathe it, is about 80% nitrogen; therefore, you can mix the two, as nitrogen filled tires are more of a pure gas. Nitrogen won?t fluctuate as much as regular air, and in the long term, will be better overall for the compounds of the tire.
Q: Do I ever need to replace the TPMS sensor itself?
A: With TPMS systems operating at a 315mZ in the United States, and these sensors being battery operated, they can need replacement in time. Typical shelf life for a TPMS sensor battery is 5 to 7 years. Most tire and wheel vendors can get you the sensors cheaper than dealerships. Most reputable tire and wheel shops will install the new sensors and program them if you pay for the installation of the tire and wheel itself.
What is a Tire Pressure Monitoring System?
A tire pressure monitoring system is an electronic device that sits inside your wheel, and monitors a tire?s air pressure via a small transmitter built into the sensor. By federal law, all vehicles built after September 2007 are required to have the system in place. In relating this to your STi, the sensor will send off a radio frequency, alerting you via a small light on the gauge cluster. In your Subaru, the TPMS light can come on by one tire being as little as one pound (1 PSI) low, or there being a fault in the tire pressure monitoring system.
Tire Pressure Montoring System Sensor
TPMS Light On
How Does TPMS Affect My Car?
The TPMS system is required by federal law after 09/01/07 build dates, aimed at preventing tire blowouts and promoting better gas mileage. In theory, this will decrease the amount of accidents related to tire blowouts, and decreasing the amount of gas cars will use due to having underinflated tires. TPMS sensors in your Subaru weigh about the same amount as a pen, so they?re not a benefit to true weigh reduction.
That Annoying TPMS Light Always Comes On!
The TPMS light (pictured above), can come on if your tires are underinflated by 1-2PSI. Instead of removing the TPMS sensors, inflate the tires 3PSI higher than the door placard states (on a cold tire); 3PSI will not affect how the tires will wear on an OEM spec Subaru. If you have your car set up for lower, or extremely higher air pressures for specific events, the light will stay on regardless.
What Should I Do to Maintain the TPMS System?
The manufacturer that makes Subaru?s TPMS system, Schrader USA, recommends replacing the TPMS valve stem every time the tire is dismounted from the wheel. From my experience in the tire industry, whether talking to the Tire Industry Association (TIA) guys, or representatives and engineers from tire manufacturers such as Michelin, Bridgestone, and BF Goodrich, they recommend installing the new TPMS valve stem whenever you get a new set of tires, or every other seasonal exchange. The new valve stem for a TPMS system, typically called a service pack, can run anywhere from $2.50 to $5.00 from most tire vendors.
Subaru TPMS Valve Stem
Frequently Asked Questions:
Q: Can I remove the Tire Pressure Monitoring System Sensors from my car?
A: Yes, but many tire dealers and vendors hesitate to remove them, or install them on a car that should have them due to federal laws and regulations. Essentially, you?re asking them to remove a safety feature.
Q: Does having air or nitrogen in my tires affect the sensors, and can I mix the two?
A: Air as we breathe it, is about 80% nitrogen; therefore, you can mix the two, as nitrogen filled tires are more of a pure gas. Nitrogen won?t fluctuate as much as regular air, and in the long term, will be better overall for the compounds of the tire.
Q: Do I ever need to replace the TPMS sensor itself?
A: With TPMS systems operating at a 315mZ in the United States, and these sensors being battery operated, they can need replacement in time. Typical shelf life for a TPMS sensor battery is 5 to 7 years. Most tire and wheel vendors can get you the sensors cheaper than dealerships. Most reputable tire and wheel shops will install the new sensors and program them if you pay for the installation of the tire and wheel itself.
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