The What, Why and How of Tire Pressure Monitors

October 20, 2017 •

Tire Pressure

Ever had a tire blow out? It’s a frightening experience, and one that a tire pressure monitoring system (TPMS) is intended to prevent. Every car sold since 2008 has a TPMS, but most drivers remain unaware of it until a yellow warning light turns on.

When that happens, the driver should pull over, look in the manual to see what it means and then head to a car dealership or tire center. Unfortunately, the more common reaction is to listen for anything obviously going wrong, and if it isn’t, keep driving. That’s a mistake. Here’s why.

Why Tire Pressure Monitors Exist

Under-inflation is a problem.

The sidewalls of a tire flex constantly as you drive. That fatigues the rubber and builds up heat. A tire with too little air flexes more, gets hotter and eventually fails, but that’s not the only problem.

An under-inflated tire has more rolling resistance, and that alters how a vehicle handles and brakes. Take a corner at speed and the tire with low pressure deforms more than the others. In an extreme case it could even make the vehicle tip over.

How Tire Pressure Monitors Work

Vehicle manufacturers use one of two technologies.

  1. Direct
    • A combined pressure sensor/transmitter in each wheel sends pressure information to a receiver in the vehicle. If it’s too low, the warning lights up.
  2. Indirect
    • These measure the rotation speed of each wheel. An under-inflated tire turns at a different speed to the other three and the system uses this to decide when to put on that light.

When Tire Pressure Monitors Need Attention

Most of the time you won’t notice your tire pressure monitoring system. However, there are three situations when you’ll need to pay attention.

  1. If the light comes on.
    • Stop when it’s safe and see if you can tell which tire is the problem. Change it yourself, or drive – slowly – to a garage and get some air put in.
  2. When you get new tires. Especially if switching from summer to winter rubber.
    • The people fitting your tires usually take care of the tire pressure monitoring system, but watch for that warning light in case they forgot.
  3. When your car gets inspected.
    • Some states require that TPMS be operating the way the manufacturer installed it. If it isn’t, you could have a problem.

TPMS is an important safety system. If that light comes on, don’t ignore it. To ensure your time on the road is smooth and safe, check out our other tire tips today.