MOST people don't think too much about their car's tires - all they know is that they're round, hold air, and essentially keep the car on the ground.
In fact, most people don't even care about them, until it's time to replace the tires, then they make comments like "Gosh, my tires are worn out, now I have to replace them!" and "it's a hassle to get a whole set of new tires."
As a result, people just end up just searching 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 that 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 automobile.
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 that the tire is designed for either passenger car or light truck application.
Some SUVs and smaller trucks are fitted with P rated tires for improved ride comfort, but if you are routinely carrying heavier loads, an 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. But keep in mind, this measurement is from the widest point to widest point and not just the surface of the tread.
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 that 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 that 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. Tire companies have designed tread patterns that can greatly increase one or more of these aspects.
Aside from the amount of highway driving you do and how much cargo you carry, it's wise to consider the area you live in. If you live in a part of the country where snow is inevitable, then snow tires are recommended. Having a good set of snows in the winter will allow you to equip a more focused summer tire the rest of the year. An all-season tire will offer a moderate level of traction in all conditions, but is a compromise to the optimum capabilities of the dedicated tires.
For performance seekers, upgrading you tires offers a quick and cost effective means for improvement. The most common practice is plus sizing. This is the concept of increasing the wheel size by an inch or two while lowering the aspect ratio of the tire. This makes the sidewall shorter and more rigid. Typically, the width of the wheel and tire are also increased. Mixed with high performance rubber, the driver will notice quicker steering response and cornering ability. In fact, the level of performance you can gain can be quite astonishing - something people don't think about when trying to upgrade or update their older cars.
Using the example car tire size, we could switch to a 235/50R17, or even up to a 245/45R18 from the original 225/60R16 size. As you can see, the width of the tire and wheel diameter are increased while the aspect ratio is decreased to keep the tire's overall diameter the same.
Keeping the overall diameter as close to the original as possible is important in order to maintain sufficient ground clearance, appropriate driveline gearing and accurate speedometer/odometer readings. Large changes in diameter could also affect the car's ABS, traction control and vehicle stability systems.
The last point to consider is price. Tires may seem quite costly, but you need to keep those costs in perspective.
You will likely only need to purchase a new set of tires once or twice over a car's lifespan. You will definitely need to change the oil and other fluids many times. From that point of view, prices come much more in line with the other costs of regular maintenance.
With so many tires to choose from, even armed with this knowledge, selecting a specific tire can still be a daunting task.
Recently I had an opportunity to experience what it would be like to upgrade a set of tires. Two experiments were performed: upgrading a 2012 BMW X1's standard 18-inch Goodyear tires to 19-inch Continental DWS tires (with a lower profile) and replacing original 2013 Audi S4's Continental summer tires with a set of high performance Continental DWS all-season tires (of the same size).
In the first case, upgrading to larger, lower aspect ratio tires in the BMW X1 produced sharper capability around corners, quicker steering feel and a more "planted" feel. This happened with very little loss of comfort or noise level.
In the second case with the Audi S4, it was surprising to find out that the high performance all-season tires from Continental (DWS) performed almost as effectively as the summer Continental tires from the same manufacturer (DW) in all kinds of road conditions.
This experiment allowed me to conclude that if you buy a set of highly capable tires - like the Continental ExtremeContact DWS high performance all-season tires - you can have the cake and eat it too in a sense that you get the best of both worlds: high performance character with all-year-around capability. I think the ExtremeContact DWS is one of the best tires to consider should you wish to inject a bit of personality into your current vehicle.
Next time you find yourself in a situation that requires a set of new tires, get excited and say, "wow, it's a chance to get something amazing to improve my ride and performance," instead of sighing about spending money. It's well worth the investment.
