Tires 101

Tires are black, round, rubber and you can buy them anywhere. What else is there to know?

According to David Champion, the Director of Consumer Reports' auto testing facility, that's the attitude a lot of people take when buying tires, and it's a mistake.

He says people buy a $30,000 car and try to save $10 on tires, but those tires can transform how your car drives and handles. And, it's the most important safety feature on your car.

When buying tires, Champion suggests that consumers look for four things:

• How well the tires stop on wet and dry surfaces
  
• How much gas the tires use (some tires create more resistance and thus use more gas)
  
• How quiet a ride the tires provide
  
• How smooth a ride the tires provide

Champion says you may need to invest in a winter tire if you live in an area that gets a reasonable amount of snow and you really need to be out and about. There have been big improvements in snow tires. In the 1970s, snow tires simply had big chunky treads. Now, new technology for winter tires uses special rubber compounds that allow the tires to flex in different ways and better grip the road.

Consumer Reports tested tires and listed three as their top picks. They are:

• Dunlop SP Sport A2
  The touring-performance all-season tire is an "H-rated" tire, which means it's designed for speeds up to 130 mph. "Touring-performance" is the industry term for high-performance tires. Although drivers don't need to reach this speed, the H-rated tire provides improved handling and grip at all speeds.
• Goodyear Eagle Ultra Grip GW-2
  This is the H-rated winter tire choice. Consumer Reports says the tire is an excellent all-around choice and gives the best dry and wet braking among H-rated tires. They also say it is the best ice-braking tire for cars without ABS (anti-lock braking system).
• Kumho I'zen Stud KW-11
  This is the Q-rated winter tire choice. Q-rated means the tire is designed for speeds up to 99 mph. These tires are cheaper than H-rated. Consumer Reports says: "An excellent choice where snow is less severe. Best dry and wet braking among this group."

Champion says most drivers fail to buy good tires and maintain them properly. He recommends checking tire pressure once a month. Be sure to fill your tires as directed in the owner's manual and as noted on the driver's door. Do not follow the number printed directly onto the tire. During the monthly check-up, you should also run your hands over the tire, feeling for bulges or other abnormalities.

Champion explains that the four most common tire maintenance mistakes and effects are:

• A tire that's under-inflated will wear on the outside edges of the tire
  
• A tire that's over-inflated causes the center of the tire to wear faster
  
• A car out of alignment causes the tire to wear more heavily on one side than the other.
  
• A tire damaged by hitting a pothole may have a bulge

Through normal wear and tear, a tire's tread will wear down. When the tread is too worn, it's time to buy new tires. The number of miles you can expect to put on a set of tires before they reach this point varies widely. Some tire treads are quite soft; others are intended to endure extensive driving. When shopping for tires, this is yet another variable to consider to find the best match for your driving style.

There are two ways to tell if your tread is still at a safe level. First, look for the tread-wear indicator bar that appears on all tires. This bar is set at a 90 degree angle to the tire and is 1/16 of an inch higher than the rest of the tire. When the bar is even with the tire, the tire needs to be replaced. The other way to check your tire's tread is to take a penny and insert Lincoln's head into the tread. If any of his hair is visible, the tread has been worn too low and the tire should be replaced.

Champion recommends replacing all four tires on a vehicle at the same time. If you find that your front or back tires wear faster, rotate the tires so that they wind up wearing evenly.

Consumer Reports also investigated the best places to buy tires. Overall, where you buy depends on your motivation — are you more concerned with price or convenience?

The researchers found that mail-order retailers and independent tire deals had the lowest prices. However, buying a mail order tire requires more legwork. Consumers have to take the tire somewhere to have it mounted and balanced. Also, ordering through the mail may not be a good option if you need to replace the tire immediately. Warehouse clubs such as Costco and Sam's Club did not sell three of the five tires that Consumer Reports was comparing and their prices were not much cheaper than Sears or Wal-Mart.