Underinflation of a tire affects driving performance, wears the tire out more quickly and reduces fuel efficiency. An under inflated tire can't maintain its shape and becomes flatter than intended while in contact with the road. Not only does this put you at risk of getting a flat tire, it significantly shortens the life of your tire. That’s why you should frequently check your tire pressure to make sure all four contain the prescribed air pressure (usually indicated on a sticker on the interior edge of the car door).