A tire dealer or auto repair shop will need to remove the tire from the wheel and inspect it for damage, both inside and outside, before deciding whether or not it can be repaired.

Even without damage, all tires need to be replaced as the tread wears. Since it's recommended you check your tires' air pressure once a month, that would also be a good time to check for signs of damage and wear. Make sure all the tread is wearing evenly - if one side is bald or is visibly wearing faster than the other side, you may need your tires balanced or rotated.

Tires should be replaced when they are worn down to 2/32-inch of tread. A simple way to test this is to use a penny. Place the penny in the shallowest tread groove with Lincoln's head pointing down. If you are able to see the top of his head, your tire needs replaced.

Understanding Tire Sizes and Types
Once you've determined you need new tires, you need to know the correct size and type of tires to look for.

The tire size for your vehicle can usually be found on a sticker in the driver's doorframe, with the sticker being visible when the door is open, or in your owner's manual. You can also determine a tire's size by reading the series of numbers and letters on its sidewall.

For example, let's say your tire's sidewall reads: P215/65R15 89H.

• "P" stands for the type of tire - in this case, passenger. If you drive a truck or SUV, the sidewall code would begin with "LT" for light truck.
• The "215" in this example represents the tire width, or 215mm measured from sidewall to sidewall.
• "65" shows the tire's aspect ratio, or the height of the tire's sidewall compared to its width. In this case, 65 means the height is equal to 65% of the tire's width.
• "R" simply means the tire's construction is radial, and the plies run radially from bead to bead.
•  "15" is the wheel's diameter - in this case, the width of the wheel from one end to the other is 15 inches.
•  "89" shows the tire's load rating, and "H" shows its speed rating. Both these ratings correspond to actual numbers in charts established for the tire industry. In this case, a load index of 89 means the tire can support 1,279 pounds at maximum air pressure, and an H speed rating means the tires can travel at a maximum speed of 130 mph. Load index and speed rating charts can be found by searching the Internet, but tire dealers also will be able to tell you which tires will suit your vehicle's needs.

Next, you need to determine the correct type of tire for your vehicle. There are many to choose from, including summer, all-season and winter tires, as well as high performance, performance, touring, etc.

Your new tires, first and foremost, must meet your driving needs. Think about the best and worst conditions in which you'll be driving. Do you live in an area where winters bring snow, ice and prolonged temperatures below 45 degrees? If so, you may want to consider installing winter tires during winter months, and summer or all-season tires during warmer months.

Does your area see heavy rain, where you'll be driving on wet pavement a lot? If so, make sure you opt for a tire that has good wet handling capabilities.

As far as ride comfort, do you prefer a soft, cushioned ride, or would you rather have a stiffer tire with crisp handling for sportier driving? Touring tires provide a softer ride compared to performance tires or ultra-high performance tires, which are designed for sports cars or drivers that are a little more demanding when it comes to vehicle performance.

The more specific information you can tell your tire dealer, the better off he or she will be in helping you select the best set of tires for your vehicle. This includes sharing your preferences for road noise, fuel economy and the number of miles you'll be able to drive on the tires. Tire dealers are experienced in choosing tires for just about any type of driver, and they're also well versed in customer feedback about most of the tires they stock.

Making a Tire Purchase
Now that you know what type of tire you're looking for, it's time to compare brands and prices. It's also important to compare any treadwear warranties, customer satisfaction warranties or manufacturer's warranties.

As with most anything else, often you get what you pay for when it comes to tires. Depending on the size and type you need, tires to fit your vehicle will probably be available with quite large price differences. This is where it's important to compare treadwear warranties, since you can be fairly certain a tire with a 40,000-mile warranty won't last as long as one with an 80,000-mile warranty.

When considering price points, take into account the age of your car, how much longer you're planning to keep it, how many miles you typically drive, and how often you want to go through the process of replacing tires. Also, remember that premium, top-tier tire brands tend to be more pricey, but that doesn't mean that a mid-tier, slightly lower priced brand doesn't offer a quality tire.

Once you've done your research, check with your local tire dealer to get his or her opinion on the tires you're considering. For detailed information about specific tire lines, visit that manufacturer's Web site.

Also, for more tire buying tips, as well as tire care and maintenance topics, check out tiremakers' Web sites; most offer easy-to-understand tutorials. Here are a few that offer sections specifically for buying new tires:

• michelinman.com 
• tiresafety.com 
• goodyeartires.com 

Denise Koeth
AskPatty expert woman

Denise Koeth is the managing editor for Babcox Publications' Tire Review magazine. She also serves as an assistant editor on Tire Review's sister publication, Fleet Equipment magazine.

A veteran reporter, Koeth started her career at the Barberton (Ohio) Herald and most recently worked for the Medina County Gazette. She graduated with honors from The University of Akron, earning a bachelors degree in mass media communications.

Creative commons photo credits:
Artistic bald tire courtesy of alvimann at morguefile, artistic flat tire courtesy of alvimann at morguefile,
artistic tire tread courtesy of xpsquid at morguefile, and rainy road courtesy of pindyath100 at morguefile.

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