Most people don't think too much about their car's tires - all they know is they're round, hold air and essentially keep the car on the ground. In fact, most people don't even care about their tires until it's time to replace them.
People typically search for the "best" deal, often getting the cheapest tires possible.
If one would stop and think about their tires a little longer, they would realize they are the only contact their vehicle has with the road. Therefore, stopping distance, cornering ability, ride comfort and fuel efficiency are all affected by the tire choice - to a significant degree I might add.
The most sophisticated braking and steering systems could be rendered useless by inferior tires. But by the same token, a good set of tires can considerably improve every aspect of even the most basic auto-mobile.
Now that we've acknowledged the importance of tires, how do we go about making the correct choice?
As with any purchasing decision, knowledge is power.
The first step is determining what size of tire you need. Just like how different people need different sized shoes, different cars need different sized tires.
But unlike shoes, which are largely defined by a single number and restricted by your feet size, tires are exponentially more complicated with an infinite combination of size, diameter, compound type and character.
Let's look at two examples: P225/60R16 97T and LT265/70R17 121R.
Admittedly, these appear a bit like a code, but after breaking the measurements down, it's not so bad.
The prefix, a P or LT, simply indicates the tire is designed for either passenger car or light truck. Some SUVs and smaller trucks are fitted with P rated tires for improved ride comfort, but if you are routinely carrying heavier loads, a LT rated tire would suit your needs better.
The next group of digits, 225 and 265 in our examples, tells you how wide the cross-section of the tire is in millimetres. The bigger the number, the wider the tire.
The following number is the aspect ratio. This tells you the height of the sidewall as a percentage of the tire's width. So, the sidewall of our passenger tire is 60 per cent of 225 mm, or 135 mm. Understanding the aspect ratio becomes most important when changing wheel sizes, which we will discuss in more detail later.
The R lets you know it is a radial tire as opposed to a bias-ply tire, which would be designated by a D. Bias-ply tires are no longer used in passenger vehicle applications.
The rim size in inches is noted next. In our examples, the car has 16-inch wheels and the truck has 17s. Obviously, a 16-inch tire will not fit on a 17-inch wheel or vice versa.
Next is the load-carrying capacity. As you can see in our example, the LT has a higher load rating at 121 versus 97 for the passenger tire. It is highly recommended you never select a tire with a lower load rating than the manufacturer's specifications. But as mentioned earlier, it is acceptable to increase the rating if you are often carrying a lot of weight.
The last item is the tire's speed rating. This reflects the tire's ability to dissipate heat. Driving at high speeds for extended periods of time, like on long highway commutes, creates heat buildup within the tire.
Too much heat increases the likelihood of a failure. Again, do not fit a tire with a lower speed rating than the one recommended, but if the bulk of your driving is on the highway, feel free to move up a rating or two.
Now that we've broken down the basic ingredients of a tire, we need to determine what makes one better than another. Well, that largely depends on your specific needs.
Some questions you need to ask yourself are: Would you prefer a harder, more performance oriented tire or a softer, more comfortable one? Also, how do you rate the importance of fuel economy, tread wear and noise reduction?
