Maintaining Fuel Economy: Understanding Tire Pressure's Role

Fuel economy is a key consideration when buying a car, and it's something that should be maintained through proper vehicle care. One of the most important factors in achieving good fuel economy is tire pressure. Properly inflated tires can improve fuel efficiency, while underinflated or overinflated tires can negatively impact fuel consumption. Tires with too much or too little air will have an uneven surface area in contact with the road, increasing rolling resistance and causing the engine to work harder, which in turn burns more fuel. This simple maintenance task can make a significant difference in fuel costs and vehicle performance, and it's easy to do with a tire pressure gauge and inflator.

Recommended pressure improves fuel economy

Maintaining the correct tire pressure is essential for keeping you and other road users safe, improving vehicle performance, and decreasing fuel costs. Underinflated tires are among the leading causes of tire failure and increase your vehicle's drag, which increases fuel consumption.

Tires naturally lose 1 pound per square inch (PSI) of pressure per month, and for every 1 PSI drop in your average tire pressure, you lose about half of a percentage point of efficiency in your fuel economy. A study by the National Highway Traffic Safety Administration (NHTSA) in the USA found that every 1% decrease in tire pressure correlated with a 0.3% reduction in fuel economy. Underinflation of the tire by 10% increases fuel consumption by 2%, and 20% under inflation increases fuel consumption by 4%.

The U.S. Department of Energy found that keeping your car tires at the recommended pressure can improve your gas mileage by up to 3%. This results in significant savings over time. For example, if you fuel up once per week, this could save you almost $125 annually.

To maintain optimal tire pressure, you should check your tire pressure at least once a month and more frequently during significant weather changes, as temperature fluctuations can significantly affect tire pressure. You can find the recommended tire pressure for your vehicle in the owner's manual or on a sticker located on the driver's side door jamb or glove box door.

Under-inflated tyres increase fuel consumption

Under-inflated tires increase fuel consumption. This is because fuel economy depends on reducing resistance so that your car can move more easily. If your tires are underinflated, they become saggy and soft. The softer your tires are, the more rolling resistance there is between the road and the rubber. This means that your engine has to work harder to move your car, burning more fuel and increasing your fuel costs.

The U.S. Department of Energy states that keeping your car tires at the recommended pressure can improve your gas mileage by up to 3%. For example, if gas prices are $4.00 per gallon, you could save $2.40 every time you fill up a 20-gallon tank. If you fill up once per week, that's an annual saving of almost $125.

Additionally, underinflated tires can cost you money in other ways. The U.S. Department of Transportation figures show that under-inflated tires waste about 5 million gallons of gas every day in the United States. Furthermore, for every 1 psi missing from your car’s set of 4 tires, you lose 0.1% of your gas mileage. This means that by properly inflating your tires, you can improve your gas mileage by 3.3%.

Under-inflated tires also wear out faster. Every psi lost means that tires wear 10 percent faster. This costs you money in the long run, as you will have to replace your tires more frequently.

Finally, underinflated tires are a safety issue. They can lead to longer stopping distances, poor handling, and dangerous blowouts on the road.

Over-inflated tyres are unsafe

Maintaining the correct tire pressure is essential for fuel economy and safety. Fuel economy depends on reducing resistance so that your car can move more easily. If your tires are underinflated, they become saggy and soft, increasing rolling resistance and causing your engine to work harder, which in turn burns more fuel.

Keeping tires at the recommended pressure can improve gas mileage by up to 3%. Conversely, underinflated tires can lower gas mileage by about 0.2% for every 1 PSI drop in average pressure.

While underinflated tires are a safety issue, overinflated tires are unsafe, too. Here's why:

Loss of Traction and Grip

Overinflated tires cause the center of the tire to bulge, resulting in a smaller contact patch—the section of the tire touching the road. This reduced contact area leads to a loss of traction and grip. As a result, you may experience longer braking distances and a tendency for the car to slide while cornering.

Excessive Wear on Center Treads

The smaller contact patch means that the center treads of the tire bear the brunt of the work, leading to excessive wear on the center treads compared to the outside and inside treads. This uneven tread wear can result in legal issues if the center treads are worn beyond the minimum legal limit, even if the outer treads are still within the acceptable range.

Uncomfortable Ride

Overinflated tires are stiffer and less flexible than properly inflated ones. This stiffness results in a bumpier ride as more of the shocks from the road are transferred to the occupants of the vehicle.

Odd Vehicle Behavior

Modern vehicles have electronic stability control systems, ABS, and traction control that are calibrated to work optimally with tires inflated to the correct pressure. Overinflated tires can cause these systems to receive incorrect signals from the wheels, leading to erratic behavior and potentially dangerous responses from these safety systems.

Increased Risk of Blowouts

The increased pressure in overinflated tires makes them more susceptible to blowouts, similar to how a balloon becomes easier to pop as you add more air. A tire blowout, especially at high speeds, can be extremely dangerous and even fatal.

In summary, overinflated tires can compromise your safety, comfort, and vehicle performance. They can also lead to increased tire wear and higher fuel consumption, costing you more money in the long run. Therefore, it is crucial to maintain the correct tire pressure as specified by the vehicle manufacturer.

Temperature affects tyre pressure

Tyres are filled with pressurised air, which is subject to the laws of physics. As a result, temperature changes will affect tyre pressure. Warm air increases pressure, and cold air lowers it. For every 10°C change in temperature, tyre pressure changes by 1 to 2 PSI. This can result in a difference of up to 15% between summer and winter tyre pressures.

The ambient temperature is the main cause of these pressure changes, but other factors, such as friction from the road surface, can also play a role. Friction and resistance cause a build-up of heat inside tyres, and this warming effect adds further pressure.

While tyres are designed with built-in air pressure tolerances, it's important to monitor their pressure and watch for signs of overheating. Overheated tyres can be identified by touch—if they're hot, they're close to overheating. It's important to let them cool down, as the hotter a tyre gets, the higher its pressure, and this can lead to underinflation when the tyre cools.

Cold weather can also cause issues. If a car has been sitting in low temperatures for a long period, the tyre pressure will have dropped significantly. This pressure drop is often compounded by natural leakage, as air slowly escapes. Low-pressure tyres can become damaged more easily and wear out more quickly, increasing the likelihood of punctures. They also experience greater rolling resistance, which can reduce fuel economy as the engine has to work harder.

To maintain optimal fuel economy and vehicle performance, it's recommended to check tyre pressure regularly, at least once a month or every two weeks. It's also important to ensure tyres are inflated to the correct pressure, which can be found in the vehicle's manual or on a sticker in the car.

Regular checks save money

Maintaining the correct tire pressure is an easy way to save money. It is a simple procedure that can be done with a tire pressure gauge, and it can make a significant difference to your fuel economy. By keeping your tires at the recommended pressure, you can improve your gas mileage by up to 3%. This is because underinflated tires increase rolling resistance, making your engine work harder and burn more fuel.

Tires naturally lose 1 pound per square inch (PSI) of pressure per month, so regular checks are essential. The ideal frequency for these checks is once a month or before long trips. It is also a good idea to check your tire pressure with every season change, as temperature fluctuations can significantly affect tire pressure. For every 5°C drop in temperature, there is a 2% loss in tire pressure, so a drop in daily average temperature from summer to winter could result in 5-10 PSI underinflation.

You can find the recommended tire pressure for your vehicle in the owner's manual or on a sticker located on the driver's side door jamb or glove box door. It is important to note that the PSI stamped on the wall of the tire itself is the maximum air pressure, not the optimum pressure.

By keeping your tires at the correct pressure, you will not only save money on fuel, but you will also extend the lifespan of your tires by reducing unnecessary wear and tear. This simple routine of inspecting your tires and keeping the proper PSI could save you hundreds of dollars over the life of the tires.

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