By: JERRY EDGERTON
It depends on what you're driving and how you treat it.

         Decades of improvements in auto design, combined with tough drunk-driving and seat-belt laws, have made it much safer to be on the road. Since 1979, highway traffic deaths have dropped by half. Still, more than 40,000 people die in auto accidents each year. Many of the victims are young; motor-vehicle crashes are the leading causes of death among Americans of every age from  six to thirty-three.  To keep your car as safe as possible, don't neglect what matters most on the road-tires, brakes, air bags and seatbelts. "Modern cars are so trouble-free that people have forgotten that vehicles need maintenance" says David Van Sickle of the American Automobile Association (AAA). " Failure to check tire pressure and do other maintenance can have serious safety consequences."  Here are some safety tips to live by.

Tires  Tires that don't have enough air can kill you. Under-inflated tires flex  too much and build up heat, which can lead to blow outs, and tread separation, where the tread peels away from the tire. Tread separation set off the recent Firestone tire recall.  Pressure just a pound or two per square inch (psi) too low can be dangerous. With such narrow margin for safety, it's important to check pressure at least monthly. Auto-safety experts agree that you should follow your carmaker's recommendation for air pressure, not the tire manufacturer's. That number is usually posted on a plaque on the driver's side door pillar, inside the glove compartment and/or in the owners manual. On some brands, it may be inside the gas-cap cover.  Gauges at services stations are often inaccurate, so consider buying your own gauge at an auto-parts store ( they cost about $5 ).  Test pressure before the car has been driven. If you must add or subtract air, retest the tires afterwards.

Warning Signs  If  when driving at highways speeds you hear a muffled thumping  noise from your tires, you may have tread separation that requires immediate attention-or even a flat. Check tire condition every six months by sticking a penny into the tread. If the tread does not reach the top of Lincolns head, you need new tires. Tires usually last 40,000 to 80,000 miles, depending on quality.  If you feel a shimmy in your steering wheel, your wheels may be out of alignment. This can cause tires to wear prematurely. It's prudent to have a mechanic check your alignment as your car-makers suggests.

Ratings Count  Government ratings are generally noted on the side of a tire-for traction, AA is best, C is lowest. Or you can check the website of the National Highway Traffic Safety Administration at nhtsa.gov/cars/testing/tirarate. If you drive long periods at high speeds or with heavy loads, you should have your tires rated B or better.

Brakes  It use to be that brakes needed to be replaced when they squealed. It's not that simple anymore. Newer cars with anti-lock braking systems (ABS) automatically check them with computerized diagnostics as soon as you start the car. That's why its important to watch the brake's dash board warning light. If the light goes out after about two seconds, the system is working properly. If the light stays on, see a mechanic.   If you hear a squeal or grinding noise-even if you can stop on a dime-it means that, at a minimum, the brake pads or shoes need replacing. IF the car pulls to one side, that's also a trouble sign.     You need a brake over haul every 30,000 miles in any event-possibly sooner, depending on driving conditions. It's best to use a mechanic certified by the National Institute for Automotive Service Excellence (ASE). Look for an ASE sign, or check for shops using certified mechanics at ascert.org.

 Air Bags  These devices have been required in all vehicles since the 1998 model year. They have saved nearly 5000 lives, according to the NHTSA. But air bags have also been linked to 170 deaths, which means it's prudent to maintain this safety device and position yourself properly.

Maintenance  Every time you start the car it runs a diagnostic test of your air bags. If the air bag light stays on, the bag should be checked at a dealership.  If your air bag equipped car is more than ten years old, I'd recommend bringing it in for a test. Though the bags should still be functioning properly, extra caution never hurts.  Should you need to replace an air bag, make sure you ask for-and receive-a new one. There's a vigorous trade in used and black market air bags. The records should shoe recent shipments from a leading manufacturer such as Breed Technologies or TRW Inc. and the serial number on those records should match the serial number printed on the bag.

Sit Right  According to the NHTSA, drivers should be at least ten inches from the air bag. Anything closer puts you in danger of being hurt by the force of the air bag as it inflates. Tilt your steering wheel as far down as its comfortable, so it's pointing the bag at your chest instead of your head.

Seat Belts  Front seat belts, properly used, reduce fatalities by 45 percent, according to the federal safety regulators. Most of us assume our belts are in good condition and functioning properly, yet that isn't always the case. How can you tell if yours is offer maximum protection?

The Fit Test  The belts should unreel smoothly when you pull them, and then retract snugly around you. If they don't fit well, check the retractor-the spool-like device that tightens the belt-near the floor. "in a family car, you may find crayons or McDonald's wrappers caught in the retractor," says Van Sickle.

The Visual Test  See if your belts are frayed or torn. If you've had an accident, look for tear strips near the retractor. If the retractors are sound, and you're accident-free, the belts should last the life of the car.

The Safest Vehicles on the Road   To Determine which vehicles are safest, Money magazine crunched numbers for more than 100 cars, minivans, sport utilities and pickups. After factoring in crash-test data and injury records, the following models received the highest overall safety rating-five stars ( none of the pickups made the grade)

Small Cars:  Volkswagen /  New Beetle                           

Mid-Size Cars: Toyota Avalon / Camry,Volkswagen Passat / Volvo S70 

Minivans: Ford Windstar / Honda Odyssey /  Toyota Sienna

Sport Utilities: Toyota 4Runner                

Luxury Cars: BMW 540i /  Lexus LS 400