All new cars and light trucks, since 2008, have come equipped with a tire pressure monitoring system. The TPMS system detects when a tire becomes under-inflated and lights up a warning light on the dash. So what’s the big deal? Well, under-inflated tires can be a real safety concern. First of all, they don’t handle properly, and that can lead to an accident. And second, under-inflated tires can overheat and cause the tire to come apart, which can also lead to an accident.