As many cars now include a tire pressure monitoring system, many drivers assume that they don’t need to worry about tire pressure anymore. But your dash’s warning light doesn’t go off until a tire is dangerously low on air at under 25 percent full. While you should make a habit of using a tire gauge, these four warning signs will help you know when your tires are in need of more air:

Worn Treads

Image via Flickr by Highways Agency

Image via Flickr by Highways Agency

Consumer Reports has a great way to see if your treads are wearing out with a simple penny. If you can see the top of Abe’s head, then the tire is too worn down and you are at risk of a flat tire. And even if you don’t get a flat, your car won’t have the control it needs with bald tires.

You may not notice on a nice day, but you will as soon as it starts raining. A tire’s treads help channel water so that your tires always have firm contact with the pavement. Without this, a layer of water can form between the tire and the road, causing you to hydroplane.

Poor Handling


Image via Flickr by Gritty FIlm

When a tire is underinflated, you don’t get the firm control or the full benefit of the treads on the road. Instead, the less-protected walls of the tire can come into contact with the ground, where they will wear out and be susceptible to a puncture. Even if you don’t get a flat, an underinflated tire causes more sidewall flex, which in turn limits how well you can handle the car and how long you need to brake.

Cracking on Tire Walls


Image via Flickr by Jonathan Rolande

All tires will get cracks eventually due to age, but you can speed up the process by underinflating the tires. Changes in seasons add some age and wear to a tire, and it is natural for a tire to lose some air throughout the year. But the trouble comes when a tire is left underinflated during hot weather, when the extra friction from underinflation ages the tire even faster and can even cause a blowout. If your tires have cracks in the walls, they have to be replaced. Otherwise you are placing yourself and others on the road in danger. After all, loss of control is a high possibility when a tire blows.

Tire Vibration


Image via Flickr by pheaber

While you can inspect your tires to see worn treads and cracked sidewalls, and you may notice your car’s poor handling, one of the biggest warning signs that your tires are in trouble is tire vibration. The vibrations usually occur when your car isn’t properly balanced or aligned. One reason they wouldn’t be aligned is if one tire doesn’t have enough air. Tire and steering vibrations mean you don’t have nearly the control you want when driving, and they also kill your gas mileage. Whatever the reason, don’t put off checking your tires if this sign pops up.

What other signs of tire underinflation have you seen?