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5 Possible Reasons Your Car's Tires Keep Losing Pressure

5 Possible Reasons Your Car's Tires Keep Losing Pressure

10th Feb 2020

stem caps on tires

Losing Tire Pressure

Do your tires constantly lose pressure when driving? According to the National Highway Traffic Safety Administration (NHTSA), underinflated tires contribute to nearly 1% of all traffic-related injuries and fatalities. It's frustrating when you fill up your tires with air, only for them to deflate shortly thereafter. By understanding what causes tires to lose air pressure, though, you can prevent it from affecting the safety, as well as performance, of your car.

#1) Missing Valve Stem Caps

It's not uncommon for valve stem caps to fall off. While a missing valve stem cap may seem harmless, it can lead to loss of air pressure. Without a cap, dirt and debris will enter the valve stem where it can break through the seal. When this occurs, air will leak out of the tire through the valve stem.

#2) Degraded Valve Stem

Even if the valve stem is present and intact, a tire may lose air pressure if its valve stem is degraded. Valve stems are typically made of plastic, and although plastic is waterproof, it's not immune to damage. Over time, valve stems can degrade to the point where they no longer create a sealed environment.

#3) Puncture

Of course, a puncture in a tire will cause it to lose air pressure. Tires can only withstand so much force. If you drive over a sharp or hard object, it may puncture one or more of your car's tires. Therefore, if you're struggling to maintain an appropriate amount of air pressure in your tires, you should inspect them to see if they are punctured. Spraying the tires with soapy water will cause bubbles to form around the breach, allowing you to identify punctures more easily.

Common sources of tire punctures include the following:

  • Nails
  • Screws
  • Broken glass
  • Sharp rocks

#4) Cold Weather

You might be surprised to learn that cold weather can cause tires to lose air pressure. For every 10 degree drop in the temperature, tires lose about 1 to 2 pounds of air pressure. If the temperature drops 20 degrees overnight, you may lose up to 4 pounds of air pressure in each on your car's tires.

#5) Misaligned Wheel Mounting

The way in which your car's tires are mounted to their wheels can affect whether or not they lose air pressure. For a sealed environment that prevents loss of air pressure, a tire must be mounted so that it's aligned with the wheel. If a tire is misaligned with the wheel, air pressure will leak through the sides.