Here's Why Your Tire Pressure Warning TPMS Light Came On & What To Do Next

Winter arrived in the United States and Canada this week. Temperatures dropped from 60F to 18F in the Boston area. In 6 hours. The reason your TPMS light most likely just came on is physics, not a leak. All gases increase and decrease in direct proportion to temperature and volume. Your tires have a lower pressure when the temperature drops. In New England yesterday, the temperature dropped by more than 40 degrees in one afternoon. That means that if your tires had a pressure of 29 psi, they now have around 25 psi. That is enough to trip the TPMS sensors in some cars. Particularly if you were close to the low setpoint before it got colder.

What To Do When Your TPMS Tire Pressure Light Comes On
If you live where the temperature has just dropped significantly from that when you set the tire pressure in your vehicle, you likely just need to add air to all 4, and hey, why not do the spare just for grins and giggles? Many new vehicles display the pressure in each tire in the gauge cluster. This is a helpful feature, but it may only work while you drive if you have some models, and others don't display it, they just alarm. So use your pressure gauge and check the pressure. You don't have a pressure gauge? Buy one on Amazon or any other way you get the stuff you need. We also suggest a portable pump that runs off your 12Vdc power socket. Or head over to a gas station and use theirs if they have one. Good luck with that.

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The proper inflation pressure for every vehicle sold in America is posted on your driver's door jam. It is NOT the pressure shown on the tire itself. We always add 2 extra pounds. It could get colder.

Now, you may discover that one tire is indeed flat. If so, call AAA or your roadside service company or kick it old school and change the tire to your spare and head over to have the tire serviced or replaced.

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Some cars use a different method to detect a low tire, but they are rare. Most now have the sensors in the wheel under the valve stems. While you are down there checking the tire pressure, why not have a look-see at the condition of your tires as well. Are they worn past the wear bars? Any bubbles, cracks or other tell-tale signs of trouble? If so, fall is the ideal time to buy new all-season tires.

In addition to covering green vehicle topics, John Goreham covers safety, technology, and new vehicle news at Torque News. You can follow John on Twitter at @johngoreham.