Buy a decent tire gauge and keep it in your car. Improper tire pressure can affect tire wear, ride and handling, and fuel economy. You should always check your tires when they are cold. Use the manufacturer’s recommended tire pressures. Tire pressure tends to rise as you drive due to heat build-up. Manufacturers have this in mind when they set the recommended cold pressures so do not let air out when the tire gets hot. Check the tire again when it cools off and you will find that the pressure is back to where it was. Tire pressure will change with the seasons, so in winter months make sure they are not under inflated. Just remember, always check them when they are cold.