Tire Pressure Monitor System (TPMS)
The Tire Pressure Monitor System (TPMS) warning light is currently required on all cars produced after 2011 by Federal law. A low tire pressure monitoring system to warn drivers of low tire pressure was prompted by a federal lawsuit when Ford Explorers were having rollover problems that caused several deaths. The investigation determined that the rollovers were caused by constant low tire pressures that played a large part in the tire blowouts and created loss of control of the SUV. Ford claimed it was due to a design flaw in the Firestone tires installed from the factory. Firestone claimed it was due to the 30 psi pressures Ford recommended for the Explorers because the lower tire pressure created a softer ride quality. Bottom line, the lawsuit brought attention to the importance of tire pressure for safety and the need for Federal regulation.
Of course in the age of cutting costs for car makers, this just added more hardware and software to the cost. For vehicles that had an original TPMS system installed for ABS (anti-lock brake systems), manufacturers were able to sense a low tire pressure by monitoring each wheel’s speed. 4 wheel ABS systems require a wheel speed sensor in each wheel. It was easy for Manufacturers to develop software that was able to “catch” a tire spinning at a different rate. The difference would most likely be caused by tire pressure. The driver would then receive some kind of warning to check all the tire pressures. These early systems were extremely limited and not reliably accurate. What if all the tires were low? The computer had no way of knowing there was an issue. And, if an issue was detected, it couldn’t tell which tire was causing the problem.
Fast Forward to Modern Tire Pressure Systems
Modern day systems have a tire sensor incorporated in the tire valve that constantly sends a signal to your car’s monitoring systems. The sensor in each valve is battery operated and has an expectant life span of approximately 10 years. Our experience at Wise Auto Clinic has shown that when the system is properly calibrated; it’s accurate, reliable and safe. It alerts the driver to check the correct tires and ultimately enhances their safety, extends tire life and increases fuel economy.
Most systems accurately report tire pressures, however sometimes it can get tricky. If an untrained service center rotates the tires or fixes a leaky valve and they don’t have the proper equipment to reprogram the system, they system no longer works! Anytime the tires are rotated the system needs to be reprogrammed. Reprogramming requires special (and rather expensive) equipment to reset the accurate tire position in your car’s computer. In our experience that doesn’t always happen.
Where this becomes a problem is when a TPMS monitoring system is alerting the driver the right rear tire is low which prompts the driver to fill it with air. The light doesn’t go out so they fill it more. Many times when we get a vehicle like this, we find the system was telling the driver the wrong tire. While simply following the warning lights, the wrong tire is now overinflated and the problem tire is still underinflated, making the problem worst.
How To Protect Your Safety
1) If your vehicle has a TPMS monitoring system, make sure you keep it working as designed. Your tire safety and Fuel Economy will pay for itself.
2) If the light is illuminated, don’t ignore it. Check to make sure your tires are up to recommended standards. Recommended pressure for your vehicle will be on a sticker inside the driver’s door jamb. If unsure, go by the tire pressure stamped on the sidewall of every tire produced. The print is small but it’s there. Most systems have a variance of 5-7 lbs.
3) Don’t always rely on a $3.00 analog tire pressure gauge in your glove box. Our experience has shown that these gauges can be off by as much as 10-15 psi. For your safety, we now only use high quality digital gauges after we discovered years ago that one of our analog gauges was off 11 psi.
4) One Final Important Tip… Just because you filled the tire up to proper pressure, doesn’t mean the light will go out. Some of the early cars require you to reset the system by a button. Most new cars will pick up the signal of proper tire pressure and turn off the light within minutes. Many cars do require driving it over a certain MPH before it will go off. You can always refer to the owner’s manual to see what your vehicle requires.
Vehicle technology is forever changing. It’s important to have your vehicle serviced by a qualified service center. TPMS systems are here to stay. As always, if you see that light, there’s a reason for it. You can always contact Wise Auto Clinic to get an honest TPMS assessment and tire recalibration.