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Q: What Does Tire Pressure Mean?

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What does tire pressure mean?

A: The air pressure that is in your tires is i...

The air pressure that is in your tires is important to many aspects of your vehicle. The air pressure can affect your ride quality, performance and handling of the vehicle, the wear of the tires, and the overall life of the tires. The pressure is known as the psi (pounds per square inch). This is the amount of air pressure that is essentially pushing out on the tire from the inside. The average pressure in most passenger car tires is about 30-35 psi, while truck tires can get upwards of 70-80 psi depending on the tire and the load that is carried. Knowing the correct air pressure for your tires, when and how to check it, as well as what kind of air to use, can improve the ride and handling of your vehicle, as well as prolonging the life of your tires.

Your tires are designed for a particular amount of air, which is based on the size and construction of the tire and the size of the vehicle.

Having too much air in the tires can cause the vehicle to ride rough due to the tires too stiff from the air pressure. This will also cause the tires to wear excessively in the center of the tread as too much pressure pushes out on the center of the tread. This can also cause the tires to have trouble gripping the road due to only the center of the tread making contact with it.

Too little air will essentially have the opposite effect. If the tire pressure is low the vehicle's ride can be too soft. This will also cause the tires to ride more on the outer edges of the tires causing them to wear out the shoulders of the tires faster than the middle. Too little air also allows the tire sidewall to flex too much during turns which drastically reduces the performance of the tire.

Both too much and too little air will also cause a tire to run much hotter than it was designed to which will decrease the life of the tire and can cause a tire to fail.

When adding air to your tires you have options as to the type of air that is used. Most air filling machines use regular air which is added to your tire. Standard air is fine but it does have its downfalls. The main issue with regular air is that it contains moisture. Over time that moisture will attack the inner liner of the tire and can get into the inner construction of the tire, causing it to fail. Standard air also had a high expansion and contraction rate which means that when the tire gets hot the air pressure can be much higher than what the tire was initially designed to have. The best option for air is nitrogen. Nitrogen is available from most professional shops. Nitrogen is a much dryer air, meaning that it does not have much moisture that can damage the tire over time. It also does not expend or contract much so the tire pressure remains more stable. The other benefit of nitrogen is that it's molecules are much larger than standard air which keeps it from leaking out of the tire much slower than regular air would. Keep in mind that these two types of air can be mixed, but you do lose the benefits of nitrogen when standard air is added to it.

Maintaining your air pressure is imperative to the life of your tire. You should be checking the air pressure in your tires about once every two weeks. This is important as air will naturally leak out from the tire at a rate of about 2 psi per week. If your vehicle is equipped with a tire pressure monitoring system (TPMS), you can easily check your pressure from inside of your car. No matter how you check your tire pressure you want to do it when the tires are cold, preferably in the morning. This gives you the most accurate tire pressure.  Always inflate your tires to the manufacturer's recommended pressure. This can be found in your owners manual, as well as on the tire pressure sticker located in the driver door jamb.

Your tire pressure may not seem like something that can have any serious affects on your vehicle. Tire pressure is typically overlooked by many people until they have to spend extra money in tires from lack of maintaining air in their tires. Making this part of your normal vehicle check can keep you safe and save you some money in the long term.

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