Discove how to know a new tyre

Make sure that you actually need new tyres. Perform a quick visual inspection. If you see excessive tread

wear, cracked sidewalls, or any discoloration or bulging, it's probably time for a new set.

If your tires are more than 10 years old, consider replacing them even if they look OK -- rubber deteriorates with exposure to oxygen.

2. Make sure that your car is in good shape. Inspect your tyres for signs of uneven wear, which might indicate alignment or suspension issues. Check for signs like more wear on the inside or outside of the tyre vs. an even wear pattern across the entire width of the tread.

If you put a new set of tyres on a misaligned car, or one with bad shocks, you're throwing money away. The new tyres will wear quickly and unevenly, and you'll need another set in a hurry.

3. Check your owner's manual and information placard. The manufacturer of your car has made a recommendation about the size and type of tyres which work best with your vehicle, that information is found in the owner's manual and on the information placard.

The information placard on your vehicle is required by law, and is permanently attached to your door edge, door post, pigeon hole door or inside your boot cover. It may have been painted over on some older cars, but it's there.

If you don't have an owner's manual, most manufacturers will sell you a replacement at a reasonable cost -- ask your dealer, or search on the manufacturer's Web site.

4. Decipher the tyre code. Perhaps the most confusing part of tyre buying is figuring out what those numbers on the sidewall of the tyre mean. They are part of a simple standardized code that is required by law in order to describe tyres, and to identify them in case of a recall.

Example of tire sidewall markings -- P215/65R 15 95H M+S

 First up is a letter or letters, indicating the tyre's purpose: "P" for passenger cars or "LT" for light trucks are the most likely letters you'll see.

 Next is a three-digit number. This is the tyre's width (in millimeters) from sidewall edge to sidewall edge.

 Then, a two-digit number which is the tyre's aspect ratio, or the ratio of height to width. The smaller the number, the shorter the sidewall.

 Next, a letter, probably "R," which indicates radial construction. Almost every tyre you encounter will be a radial nowadays, unless you're buying tyres for a classic car.

 Then, another two-digit number, which is the diameter of the wheel that the tyre is intended to fit.

 Next, an optional two- or three-digit number. This is the tyre's load index number, and its inclusion is not required by law. The load index number corresponds with the tyre's load-carrying capacity. A site for discount tyres has posted a handy chart with the load index numbers and loads. Simply put, don't install a tyre with a lower load index number than your manufacturer recommends.

 Next, a letter. This is the tyre's speed rating. Follow your manufacturer's recommendation.

 Next, some more letters, usually "M+S" or "M/S." This stands for mud and snow, and applies to most radial tyres.

There are more numbers and letters, most of which you don't really need to worry about unless your tyres are subject to a recall. They refer to the tyre's place and date of manufacture, the maximum inflation pressure, maximum load rating, composition, materials, tread wear, traction and temperature grades.

5. Consider the wheels. One of the most popular customization options on vehicles these days is a new set of rims. If your current wheels are worn or damaged, you might want to consider buying a new set when you replace your tyres.

There's more than appearance to consider when you buy wheels, however. Try to match size as closely as possible to the manufacturer's originals. Even though bigger wheels might look great on your car, there's some complicated math to making sure that the tyres and wheels match the car.