Tim's Tire Center here, and it's time to learn about your tire pressure monitoring system (TPMS). Do you know Congress became involved with the TPMS? How about the difference between a direct and indirect system? If not, keep reading about this interesting and potentially life-saving component in your vehicle.
If you need any assistance with your tire pressure monitoring system, remember you can also always see us for TPMS service.
Learn About Our TPMS Service
Your tire pressure monitoring system is true to its name; it's responsible for monitoring tire air inflation levels for passenger vehicles and light trucks. It works in real-time with your vehicle's on-board computer. If there's a problem with air pressure, your vehicle's computer is supposed to alert you in some way, often with a warning light. Whenever the air pressure drops below the recommended level, your TPMS should catch and alert you of a problem. Today, there are also systems that provide alerts for over-inflation as well as under-inflation.
Tire pressure monitoring systems are still pretty young as automotive technology. They're history has roots in the 1980s, but they really took off during the late 1990s when a series of tire failures led the United Sates Congress to implement the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act.
The TREAD Act makes it so all light vehicles need a TPMS included that will alert a driver when one or more tires, up to all four tires, is below the recommended inflation level. If you're wondering whether your vehicle is included in the light vehicle definition, it likely is. A light vehicle, under the ACT, is defined as any passenger car, multi-purpose passenger vehicle, truck, or bus with a gross vehicle weight rating (GVWR) of 10,000 pounds (4,536 kg) or less, excluding vehicles with dual wheels on an axle. The National Highway Traffic Safety Administration (NHTSA) enforces the Act, which requires that all light vehicles manufactured for sale in the United States after September 1, 2007 have a tire pressure monitoring system.
If you're not crazy about your vehicle's TPMS or you're driving an older vehicle that doesn't have one, then we have good news. You have options. Today, there are aftermarket tire pressure monitoring systems for sale that provide enhanced performance capabilities. Some even work with your smartphone. Two types of TPMS exist: direct and indirect.
DIRECT: Most vehicles use this type of system. In a direct tire pressure monitoring system, each tire gets a sensor. Depending on your system, the sensors will be located either on the inside or outside of the tires. They can be found on the outside of the valve stem, on the inside as part of the valve stem, or attached to the wheel via metal band. Each sensor is responsible for one tire and reports results to your on-board computer. Direct TPMS sensors often use a battery and have a limited lifespan. Unfortunately, you can't replace the batteries in a TPMS sensor. The way the system is designed, the entire sensor needs replacement if a dead battery is present. So when will you find yourself shopping for new sensors? It depends. The sensors work hard, recording data several times per second. A standard OEM TPMS will usually only record data when you're vehicle is running. Sensor lifespan varies depending on how often you drive and other outside factors, but they usually last between three to seven years. When bad inflation levels are detected, the Direct TPMS might send a general message or provide specific information relating to the tire in question (ex. LF 27 PSI for left front). It's important to keep in mind that a tire rotation can sometimes trigger an incorrect display. If this happens, you'll need to reset the TPMS must using your vehicle's relearn procedure. Some modern vehicles automatically relearn tire positions but others require a manual reset. Ask our team if you think you need to reset your TPMS.
INDIRECT: Indirect TPMS aren't as common as their direct counterparts; they don't rely on air pressure sensors to determine inflation levels. Instead, an indirect TPMS monitors each tire's rotational speed. The idea behind the system is as follows: an under-inflated tire has an overall diameter that is less than the other, properly inflated tires. This means the underinflated tire need to rotate faster to cover the same distance as the other tires. If the indirect tire pressure monitoring system catches a tire rotating at a different speed, it determine that there must be an inflation problem. The same is true of an over-inflated tire with an overall diameter larger than the other tires. To stay in tune with the other tires, the overly-inflated one will rotate more slowly. With this type of system, you do need to be careful of one thing: If all your tires are over-inflated or under-inflated, then you're not going to receive a warning.
Drivers across the country are pretty opinionated when it comes to the tire pressure monitoring system and how well it works. Even tire professionals have debates on the effectiveness. No matter where you stand, they're now required by law in the United States and a part of taking care of your vehicle. Remember that the TPMS is designed with the intent of safety. By alerting you to an improperly inflated tire, you may have time to react and prevent a major failure like a blowout or even tread separation. Your tire pressure monitoring system can be an effective tool.