Properly inflated tires are absolutely essential for achieving optimal fuel economy and a smooth ride. Not enough air in the tires means that more energy is required to push those wheels around, resulting in poor fuel economy. However, inflate them too much and your ride quality suffers. It's also of note that improperly inflated tires could lead to a blowout, and nobody has time for that.

NHTSA recommends checking your tire pressure every month, even if your car has a tire pressure monitoring system. Many systems will not indicate a loss of pressure until it recognizes a severe loss of pressure and fallout of the acceptable pressure range. It says that tires can lose up to one psi each month, so it's important to monitor them on a regular basis for proper tire pressure.