Do You Know WhatMeans?

The yellow symbol shown in the illustration turns out to be one many drivers don't recognize. It is the dash light symbol that comes on when a tire loses a significant amount of air pressure—normally 25% or more. This indicator light is part of a tire safety system known as a fire Pressure Monitoring System (THIS). These systems became mandatory in the U.S. for all vehicles under 10.000 pounds starting in the year 2008. From 2008 forward, vehicles sold in the U.S. must come equipped with a TPMS. This requirement comes from Congress having passed the TREAD act (Transportation Recall Enhancement, Accountability, and Documentation).

The purpose of a TPMS is straightforward: to warn drivers when a fire or tires are getting low on air. Loss of air pressure is the primary cause of tire failure, and. as obvious as that seems, it's not quite as simple as it sounds. A punctured tire (by a nail or some other object) can cause a tire failure, as most drivers know. But air pressure can drop in a tire without having a puncture too.

For one thing, temperature changes can drop tire pressure. According to safecar.gov, a vehicle safety website run for the National Highway Transportation Safety Administration. a tire can lose 1 psi in air pressure for every 10°F drop. That may not seem like much. but when you consider that the website also shows that 25% of vehicles are operated with under- inflated tires, losing another few psi when winter comes can become a serious problem.

So. the purpose of this article is simply to let drivers know—in case they don't—what the tire pressure dash light looks like (we're doing this for winter because cold weather can lower tire pressure enough to set this light off). There are two approved indicator lights (below). If you see one of these indicators light up on your dash. you will now know what it means.