Check Your Tire Pressure and Improve Your Gas Mileage

One of the easiest ways to get the best possible gas mileage out of your car is to keep its tires properly inflated. Doing so will boost your fuel economy by 3.3 percent, saving you about 10 cents per gallon of gas.

While it's easy to drive every day and assume that your tire pressure is correct, the truth is that several factors can cause tires to lose pressure over time. General wear and tear, seasonal temperature fluctuations and more cause tires to lose about 1 to 2 pounds per square inch (psi) every month. Lose 1 psi in all four tires and your miles per gallon will fall by 0.4 percent.

With today's gas prices that decline will add up fast, especially as the tires lose more pressure over time. Consider this example for a 25 mpg car driven 1,250 miles a month and $3 a gallon for gas: After five months of declining pressure, you'd spend an extra $13.80 on gas; after 10 months, an extra $51.68.

Here's how to check your tire pressure, and know what it should be:

• Look for a sticker on the inside of the driver's door, on the doorframe or in the glove box. If you don't see it in any of those places, check your owner's manual. That sticker lists the correct tire pressure for your vehicle.
• Whether the sticker says 'cold tire pressure' or not, you want to check the tires when they are cold, meaning the car hasn't been driven for a few hours.
• Don't follow the psi numbers stamped on the tires themselves. That's the maximum pressure those tires can take, not what's ideal for your specific car.
• Use a tire pressure gauge to determine the tires' current pressure level. Your best bet is a digital gauge. Digital gauges are easy to use and far more accurate than their non-digital cousins, such as the sliding gauge that looks similar to a pen. A digital gauge costs more than the latter, but will quickly pay for itself in gas savings if you regularly use it to maintain the correct tire pressure.