Proper Tire Inflation
Proper inflation pressure is necessary for optimum tire performance, safety and best fuel economy. To maintain proper inflation pressure, it is important to frequently check tires with an accurate tire pressure gauge. Any evidence of air loss or repeated under inflation would require removal of the tire and brought to a professional tire shop or mechanic for expert inspection. Tire pressure should always be maintained at the level recommended by the vehicle manufacturer's owner manual.
Under-inflation can cause many tire-related problems. Because a tire's load capacity is largely determined by its inflation pressure, under-inflation results in an overloaded tire. An under-inflated tire operates at high deflection, resulting in decreased fuel economy, sluggish handling and may result in excessive mechanical flexing and heat buildup leading to catastrophic tire failure, as well as a reduction in cornering ability, and acceleration which can significantly contribute to poor gas mileage. Over inflation can result in a reduction in the tire's ability to absorb shock during rough terrain such as potholes, which could lead to poor braking, tire blowouts or costly suspension repairs.
Determining the proper inflation pressure in a main factor in the tire's endurance and performance. Other contributing factors include temperature. Since air pressure is affected by temperature, a tire's inflation pressure can change by 1 psi for every 10 degrees Fahrenheit of temperature change. Higher temperature means increased pressure. For example, if a tire is inflated to 35 psi on an 80-degree July day, it could have an inflation pressure of 23 psi on a 20-degree day 6 months later in January. This represents a normal loss of 6 psi over the six months and an additional loss of 6 psi due to the 60-degree temperature change. At 23 psi, this tire would be considered severely under-inflated.
For safety and vehicle performance is widely recommended that tire inflation pressure be checked at least once per week, and as often as possible when tires are cold, and to take special notice of any visible damage such as bulges, punctures, cuts, cracks, irregular wear etc. This is extremely important as damaged tires due to over-inflation or under inflation can burst resulting in serious injury to yourself or others.
The American Automobile Association: Tire Maintenance
Good Year: Maintaining Your Tires