Of all the components on cars and trucks, tires are arguably the most complex mechanical devices. With a combined contact area of less than two hand-widths, tires determine whether a vehicle accelerates, stops or turns. Technological advances in design, materials, manufacturing and engineering have made tires safer, capable of handling all types of weather and road conditions and durable enough to travel 80,000 miles with no problems.

To the untrained eye, tires are round and black; for the appreciative driver who relies on tires for everyday reliability and safety, tire quality and value are more than skin deep. The tread, belts, sidewall and body plies work together to provide traction, cornering grip, durability and an air tight fit on the wheel.

Tire technology blends a unique mix of chemistry, physics and engineering to deliver a high degree of comfort, performance, efficiency, reliability and safety. A recent example is Goodyear's line of Assurance passenger-car tires with ComforTred Technology providing an extra layer of ride comfort and quietness to the driving experience and TripleTred Technology giving motoring confidence and assurance on dry, wet and icy road conditions.

Quality isn't a given. It's a trait that is tested on the road. Performance is expected over a wide range of speeds and loads with no perceptible change in vehicle handling. At Goodyear, we have continuously developed new tires with significant benefits and have integrated environment, health and safety issues into the design, production, distribution and support of our products and services.

For example, improving treadwear depletes fewer raw materials and reduces the number of scrap tires. But to ensure these gains in treadlife, motorists must take responsibility for tire and vehicle maintenance. Even the best tires can't perform if they're improperly balanced on the car and under- or over-inflated.

Inflation makes tires last longer, saves on gas money
Running a tire at 20 percent under-inflation increases a vehicle's fuel consumption by 10 percent and shortens treadlife by 15 percent. Thus, proper tire inflation helps save crude oil consumption.

Consider a 2002 U.S. Environmental Protection Agency study that states a 1 percent improvement in vehicle fuel economy saves about 1.3 billion gallons of gasoline in one year - that's more than $2 billion in fuel costs today.

In 1995, the U.S. Energy Department said under-inflated tires wasted 4 million gallons of gasoline daily or nearly 1.5 billion gallons annually in America.

A National Highway Safety Administration survey found 27 percent of passenger cars and 33 percent of trucks and SUVs had at least one under-inflated tire.

Under-inflation results in unnecessary tire stress, irregular wear, loss of control and accidents. A tire can lose up to half of its inflation pressure and still not appear to be flat.

In checking tire inflation weekly, use a reliable tire gauge and refer to the owner's manual or a placard posted on the door post or glove box. Don't look on a tire sidewall for the correct inflation pressure; the number there merely specifies the maximum pressure.

Getting it in line ensures even wear
A bad jolt from hitting a curb or pothole can affect wheel alignment and damage tires. Have a professional tire retailer check the alignment periodically to ensure that wheels are properly aligned.

Rotating extends tirelife
Each vehicle tire supports a different amount of weight, and it is this unequal weight distribution that wears tires at various rates. By rotating tires, motorists can "even out" the wear pattern and extend a tire's useful life.

During the weekly tire inflation check, motorists should examine tire tread for any uneven wear. If a pattern is detected, ask a tire retailer to check for and correct any misalignment, imbalance or other mechanical problem before rotation.

Otherwise, refer to the vehicle owner's manual for tire rotation recommendations. If none are specified, tires should be rotated about every 6,000 miles.

Checking treads for wear
Advanced and unusual wear can reduce the ability of a tread to grip the road in adverse conditions. Check tires for uneven wear every week, looking for high and low spots or unusually smooth areas. Also check for nails or other objects embedded in the tire.

Tires are produced with "wear bars" in the tread pattern. When the tread is worn down to 1/16 of an inch legally bald, the bars are even with the tread, indicating it's time for a new tire.

Behind-the-wheel habits drive long wear
To keep tires in good condition, practice good driving habits. To make tires last longer:

• Obey posted speed limits.
• Avoid fast starts, stops and turns.
• Avoid potholes and objects on the road.
• Do not run over curbs or hit tires against the curb when parking.
• Do not overload the vehicle. Check the vehicle's tire placard or owner's manual for the maximum load for the vehicle and the tires.