Tire Air Pressure Tips and Tricks

Tire Pressure Gauge
Richard Masoner/Flickr

Here's a quick tip that will have a long-term impact on the proper functioning of your car: Make sure to maintain proper air pressure in the tires.

It's certainly easy to do, but the fact is that too few drivers pay as much attention to their tire pressure as they should, especially since all new cars since 2007 are required to have built-in ​tire pressure monitoring systems. Regardless, you should check your pressure at least once a month. And never ignore a flashing tire pressure signal.

Know Your Correct Pressure

Before you can check your pressure, you need to know what the ideal number should be. Most tires will have a number for “Max. Cold Press.” embossed on their sidewalls. However, contrary to popular belief, you should not use this pressure in your tires! The correct air pressure will be on a plaque riveted inside the driver's front door. This is the car manufacturer's recommended pressure, based on the weight of the car and the tire size.

Fiddle Carefully

Many drivers like to fiddle with their tire pressures a bit, adjusting the ride firmer or softer. We don't recommend doing it. If you insist, then don't adjust too much more than a few pounds on either side of the manufacturer's baseline. Most cars now have a tire pressure warning light that illuminates if pressures are outside 25 percent of baseline. If you see that, you're fiddling too much.

Some people believe that over pressuring the tires can help protect the wheels against an impact. This is untrue. In fact, too much pressure can be as bad or worse than too little. Stiffer tires will transmit more energy from an impact to the wheels than tires that can flex a bit.

If you do fiddle with pressures, watch your tires very carefully for signs of irregular wear. “Cupping,” or too much wear in the center of the tread, is a sign of overpressure. Too much wear to the shoulders of the tire is a sign of too little pressure.

Air Pressure Varies with Temperature

To get consistent readings, always check your pressures before driving when the tires are cold. If you must add air to hot tires, leave a pound or two less than usual and recheck pressure once tires are cold. When cold weather comes around, make sure to check your pressures on frigid mornings—air pressure can drop about 1 psi for every 10-degree drop in temperature. Combined with cold-stiffened rubber, this loss of pressure can sometimes cause tires to spring otherwise unexplainable leaks.

Damage to Tires From Low Pressure

Running at low pressure on the tire for a sustained period of time can progressively damage the sidewall of the tire and cause it to fold over. Just a little bit of fold over will begin to damage the rubber. At a certain point, the sidewall will fold enough that the inner edges touch and this will start to scrub rubber off the inside of the tires, leaving the cords exposed, and handfuls of “rubber dust” inside the tire. At that point, the tire is destroyed. Again, if your car is a 2007 model or later, it will have a “low tire pressure” light on the dashboard. Learn the international symbol for low tire pressure, because it can look very confusing if you've never seen it before. The whole point of TPMS is to warn you before the damage occurs.

Air pressure maintenance is actually one of the most important repeating maintenance items on your car. Proper air maintenance will give better gas mileage, avoid irregular wear, and extend the life of your tires by thousands of miles. If it's not part of your maintenance routine—and for millions of drivers, it's not—you really should make it a monthly to-do item.