Americans spend untold millions on replacement tires, car repairs and extra gas costs due to tire neglect.

The single greatest cause of tire damage is improper inflation. Tires routinely lose pressure over time. The result of underinflated tires is early, irregular tire wear and poor gas mileage.While a periodic visual inspection of the tires in important, it is not sufficient. A radial tire can lose up to half of its air pressure and still not appear to be flat. Tires should be checked at least once a month with an air pressure gauge. A pencil-type gauge is inexpensive and can be stored in the vehicle's glove compartment.

When inflating your tires, refer to the car owners manual for the proper inflation level. The automaker has taken into account several important factors in determining the right inflation level for your car. Usually it is between 20 and 35 PSI (pounds per square inch).

While drivers can take responsibility for monitoring the air pressure in their tires, they should rely on tire dealers and auto service centers for two additional maintenance measures-rotation and alignment.

Rotating tires is important because each tire on your car supports a different amount of weight.

Improper vehicle alignment can cause irregular tread wear and hasten the need to replace tires. Alignment should be checked every 10,000 miles or at least once a year. If your car is "pulling" to one side or the other, however, you should consult your mechanic immediately.

There are several broad categories of passenger car tires made today. There are highway tires designed for use in warm weather regions, and there are snow tires specially constructed to grip snowy surfaces. One of the most popular tires sold today, the all-season radial, combines the features of both summer and winter tires.

And for performance car buffs, tire manufacturers today produce performance tires, which are designed to meet the capabilities of cars like the Corvette, Porsche or Ferarri models.

On the tire you will also see the Uniform Tire Quality Grading Standards (UTQGS). UTQGS were designed to provide information to consumers as to the relative performance of passenger tires in the area of treadwear, traction and temperature resistance.

The purpose of the standards is to help the consumer to make an informed choice in the purchase of passenger car tires. Snow tires and temporary spares are not graded under the system.

Fortunately for the consumer, reputable tire dealerships have extensive training programs for their employees for they understand the features and benefits of the various tires they carry. These sales people can explain the pro and cons of various types and brands of tires and interpret for you the UTQGS on any particular tire.

When you go to your dealer, you need to know just a few basic facts. First , you should know the make, model and year of your car and the brand name, size and type of your current tires. Also, you should inform your dealer of your preferences and driving conditions.