What to Do When the Tire Pressure Light Is Flashing
Tire pressure is critically important for several reasons. Under-inflated tires wear out faster, force the vehicle to use more fuel, hydroplane more readily, and don’t grip the road as well. Most critically, under-inflated tires can lose traction in turns and on braking, which can make everyday driving dangerous. Finally, studies have shown under-inflation, as little as 6 psi under tire pressure specification, can lead to overheating and tire blowout.
The first passenger car to adopt a tire pressure monitoring system (TPMS) was the 1986 Porsche 959, but it took a series of tire failures, as well as mounting evidence that people simply weren’t paying enough attention to this critical safety component, for the National Highway Traffic Safety Administration (NHTSA) to finally mandate direct-TPMS on all passenger vehicles in the mid-2000s.
How Does TPMS Work?
Since 2008, 100% of all vehicles on the road are equipped with direct-TPMS. Before 2008, varying numbers of vehicles were equipped with indirect-TPMS or direct-TPMS. Both systems are designed to alert drivers if one or more tire pressure readings are dangerously low.
For older vehicles, indirect-TPMS doesn’t measure tire pressure directly, but uses tire rotation speed to compare wheels and tires to each other. It can do this because tire rotation speed is directly related to tire circumference, and tire circumference is directly related to tire radius, which is directly related to tire pressure. Put simply, lower tire pressure results in a “smaller” tire, which spins faster. By comparing rotation speeds, using wheel speed sensors (WSS), the TPMS module can calculate that tire pressure is low in one or two tires.
For some older vehicles and all post-2008 vehicles, direct-TPMS is more reliable, because it takes direct pressure readings from each tire. Aftermarket direct-TPMS kits are also available, for practically any vehicle on the road. TPMS sensors, usually part of the tire valve—some are banded to the center of the wheel—directly measure tire pressure and use radio signals to communicate this data to the TPMS module.
Don’t Ignore the TPMS Light
If you have a flashing tire pressure light, it could indicate a tire pressure problem or a TPMS problem. Do not ignore the TPMS light or your tires, as this could end up costing you in extra fuel, decreased tire life, poor traction and stability, and possible tire blow outs. It only takes a few minutes to check and adjust tire pressure and reinitialize TPMS, but if the warning light keeps flashing, the best thing to do is go to your trusted tire shop for diagnosis and repair.