If You Want To Save Money On Gas, Check Your Tire Pressure

If your tires are under-inflated, you are making a driving mistake that is causing your car to use more fuel. When tire pressure drops, it takes more effort for the car to move, so the engine burns extra gas to go the same distance. The U.S. Department of Energy says keeping tires at the right pressure can improve your gas mileage by about 0.6% on average, and sometimes up to 3%. For every 1 PSI (pounds per square inch) drop in pressure (averaged over all four tires), fuel economy can drop by about 0.2%. In simple terms, if your tires are 5 PSI low, you lose about 1% in gas mileage, and if you are 10 PSI low, you lose about 2%, every time you drive.

Say you drive 15,000 miles a year in a car that gets 27 miles per gallon, you'll use about 556 gallons of gas yearly. If your tires are under-inflated, you will burn about 11 extra gallons of gas (2% fuel efficiency). At $3.75 per gallon, that means you waste around $41. If you keep your tire pressure at the right level, and get the full 3% mileage boost mentioned by FuelEconomy.gov, you can save 17 gallons of gas each year, worth about $62.60 at $3.75 per gallon. You should also endeavor to get your tires brand new, even if some tire brands manufactured in the US might cost more. It will pay off eventually.

Look at your car's recommended tire pressure. It's printed on the Tire and Loading Information label found on the driver's door edge or the door frame, and also listed in your owner's manual. This is the number set by the carmaker to give you the best ride, handling, braking, and fuel efficiency. Do not use the large number you see on the tire sidewall; it's just the maximum pressure the tire can handle. Some cars have different recommended pressures for the front and rear tires, so study the label to get it right.

Check your tire pressure when the tires are "cold." This means the car should be parked for at least three hours or driven less than a mile. Driving heats up the tires and can give you a false reading. Use a reliable tire gauge, either digital or dial. Check the pressure at least once a month and always before long trips. Don't rely only on your Tire Pressure Monitoring System (TPMS) warning light. Per the FMVSS No. 138 law, the TPMS only warns you when a tire is about 25% below the recommended cold pressure. This means your tires can be low (and you could be wasting fuel) long before the warning light turns on. Make checking your tire pressure a routine part of car care.