TPMS Light Coming On in Cold Weather? Here’s Why

If your TPMS (tire pressure monitoring system) warning light goes on during a cold snap, it may not mean your tire has a leak. That’s because cold air can affect the air pressure in your tires.


How Does Cold Weather Affect My Tires?

Tire pressure can decrease about 1 PSI (pounds per square inch) for every 10 degrees the temperature drops. It’s not due to air escaping, but rather the air inside the tire condenses, taking up less space when it's cold. This is temporary because driving will heat up the tire and increase the tire’s pressure.

Tires also lose about 1 PSI per month just from seepage of air around the edge of the rim and through the tread itself.

These two factors combined can cause the air pressure in a tire to go 25 percent below the recommended fill pressure. This is what triggers the sensing transmitters inside your tires to illuminate your TPMS dash light. Whenever your TPMS light comes on, have your air checked and bring your tires up to the proper pressure.


What Is a TPMS Light?

The tire pressure light (or low-pressure indicator) is just one part of the TPMS system. Some vehicles have two dash indicators. The low-pressure indicator looks like an exclamation point in the middle of an open-top, flat tire. This lights up when the pressure in one or more of your tires is low. The TPMS light, available in some vehicles, may light up indicating an issue with the tire pressure monitoring system, such as a dead battery in one of the tire-pressure sensors. If your vehicle does not have a TPMS light, the low-pressure icon might flash, which could indicate an issue with the system. No matter what causes your tire pressure light to turn on, come into any Les Schwab to have air added to your tires and get your system checked out.

Low Pressure Indicator Light

LOW PRESSURE INDICATOR LIGHT

TPMS System Light

TPMS SYSTEM LIGHT

Winter Tire Pressure

Temperature changes overnight or from cold winter days can affect your tire pressure. This can cause the low-pressure indicator to appear. Large swings in temperature between day and night can affect the pressure in your tires by up to 10 PSI.

The light may shut off on its own after you drive 20 minutes or so, as the air in your tires warms and expands and proper inflation level stabilizes.

Regardless, you should get your air checked right away. The TPMS light means your tires are at least 25 percent below the proper air pressure. This is a safety risk, especially if you’re carrying a load close to your vehicle’s max capacity. There’s a greater chance of tire failure, compromised handling and increased wear and tear on your tires. Your gas mileage could also suffer.


One More Reason Your TPMS Light May Go On

Your TPMS light may flash if your vehicle’s onboard computer can’t detect the sensor because you’re using a spare tire. They typically don’t have TPMS sensors.


How Do I Check My Tire Pressure?

During colder months, we recommend you have your tire pressure checked once a month. Throughout warmer months, you might not need to check your tires as frequently. You can check your tire pressure by following the steps below or by watching our video.


How to Add Air to Your Tires

Learn how to add air to your tires.

  1. Find Your Recommended Tire Pressure

    Door placard showing tire pressure

    First, look in your owner’s manual or on the inside placard of the driver’s side door for the standard cold tire inflation pressure. This number is the PSI you will inflate your tires to, as suggested by the vehicle manufacturer.

  2. Buy or Find a Tire/Air Pressure Gauge

    To check the pressure in each tire, use a tire or air pressure gauge. These often look like a metallic pencil with a sliding measuring device on one end and a tire valve connection on the other. Digital air pressure gauges are also available.

    Tire pressure gauge

  3. Unscrew the Valve Stem Cap on the Tire

    Unscrew valve stem cap

    This is typically a little black, blue, green or silver screw-cap on your wheel's valve stem. It should be plainly visible from the outside of your car. Unscrew the cap in order to properly use your air pressure gauge to check your current tire pressure.

    Note: If the valve stem cap is green, this could mean your tires are filled with nitrogen. It is okay to add regular air to a nitrogen-filled tire.

  4. Attach the Tire Pressure Gauge to the Uncapped Valve Stem

    Dial tire pressure gauge

    Stick tire pressure gauge

    From here, press the tire pressure gauge onto the valve stem and take note of the pressure indicator. If there’s a hissing sound, try removing and reattaching the gauge again for a tighter fit and more accurate reading.

    Note: If the reading on all four tires is the same as the manual’s specifications, you’re done.

  5. Inflate Your Tires (if needed)

    If any of the tires have inadequate pressure, add air until they’re properly filled. Make sure you put in the correct amount by rechecking the pressure in each tire after refilling.

    While you’re at it, check the pressure on your spare tire. You never know when you might need it.

  6. Replace Your Valve Stem Cap Once Finished

    This helps keep more air in your tires for a longer period of time, and can keep road debris (dirt and more) from getting into the valve.

    If you need help with any of these steps, stop by any Les Schwab location. Our knowledgeable technicians will perform a free visual inspection, inflate them to the recommended pressure, and help you choose the right new tires if necessary.


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