The Rolling Truth

The Rolling Truth image

Text: Tyrone I. Limon / Photos: Tyrone I. Limon, Brent Co | posted February 01, 2009 19:17

Basic facts about tires

Here in the Philippines, motorists have different reasons in changing their tires. While majority leave them as is, or 'factory stock' as often referred to, many still change them just the same. Many, most especially the young ones, go for aesthetics; while the others practicality. However, even being practical has its limits. Thinking motorists do not 'downgrade' or settle for cheaper tires, just because of the price.

So, what's the big deal?

Well, unfortunately, not many do pay attention to the correct meaning of even some of the basic tire specifications. Whether one is upgrading or merely replacing old worn out tires, understanding the various tire specifications and indicators will surely guide any motorist to make the intelligent choice. One thing to always remember is that each tire type will always have its strengths and relative weaknesses. If one is to take full advantage of the benefits of his vehicle, there really is no one-size-fits-all mentality in purchasing the correct set of tires. However, as diverse as tires seem to be, there should always be two vital considerations when purchasing: Safety and Performance.

These foremost reasons are valuable in ensuring the performance and safety of the vehicle. This information can be located at the tire wall. For instance, as indicated in the photo above.

The first number refers to the width of the tire in millimeters

The second number refers to the aspect ratio of the tire wall (the thickness is based on the width of the tire)

The third number after the R refers to the rim's diameter in inches

The fourth number refers to the load limit

The fifth indicator, a letter, refers to the speed rating

Moreover, on the sidewall, the following are also indicated: size, load and speed rating.

It is also important to look at the speed rating information. 

M - up to 130 kilometers per hour.
N - up to 140 kilometers per hour
P - up to 150 kilometers per hour
Q - up to 160 kilometers per hour
R - up to 170 kilometers per hour
S - up to 180 kilometers per hour
T - up to 190 kilometers per hour
U - up to 200 kilometers per hour
H - up to 210 kilometers per hour
V - up to 240 kilometers per hour
W - up to 270 kilometers per hour
Y - up to 300 kilometers per hour
Z - up to 300 kilometers per hour

As mentioned earlier, there are various types for various purposes. For instance, higher profiles (generally refers to the thickness of the tire wall) like the 80, 75, 70 or 65 series bring about smoother ride and longer wear. These are used for everyday city driving conditions. These also provide comfort for the occupants of the vehicle. On the other hand, these are not as responsive as lower profile tires. These tires, like 60, 50, 55, 45 and even up to 30 series, react better to sudden turns. These were inspired by the racing technology of motor sports.

It is imperative to provide the correct set of tires for the make, purpose and capability of the automobile. A vehicle with a 220 kilometers per hour potential cannot be fitted with merely 'S' rated tires. These must be proportionate to the specifications of the vehicle itself. In the same token that a pick-up truck, considered to be a workhorse for the business, cannot and must not be fitted with tires with a relatively low load capacity. Otherwise, there is the danger of overloading and exploding the tires.

More valuable information also includes treadwear, traction and temperature.

The treadwear determines the durability of the tire. The grade is usually determined in increments of 100, 200, 300, 400, 500 and 600. The higher the grading; the longer the expected lifespan is of the tire. However, there are numerous other factors to consider, such as the road (and the vehicle's) conditions, the weight of the vehicle and inflation. For example, a vehicle constantly running on a relatively rougher surface the front wheels not being properly aligned or balanced will definitely suffer prematurely from balding or uneven tire wear. With the camber being in the so-called 'positive' or 'negative' states, an imbalance instantly occurs, which should immediately be rectified. This is why manufacturers recommend that the tires be periodically checked and rotated (in some cases, including the spare). This is to maximize tire performance and meet the projected lifespan.

A vehicle's weight is also a factor in the longevity of the tire. Assuming there are two identical sedans, with car A being used daily by only 1 occupant (the driver), while car B is used by 4 full-sized adults. Most definitely, the sedan with more passengers will have its tires wear out faster because these are 'pressed harder' against the ground.

The tire pressure or inflation also plays a role in the long-term durability of these tires. Manufacturers often suggest an 'allowable range' (a low and high limit) by which motorists can select, depending on the driving condition. This refers to the maximum allowed load that the tire can support. The advantage of 'harder' or more inflated tires wear out slower and can carry heavier loads. On the other hand, 'softer' or less inflated tires are more comfortable for the passengers, most especially during long rides.

Two other basic, but just as important tire ratings are traction and temperature.

Traction refers to the tire's projected ability to stay on or maintain grip on the surface by which it is intended to do so. Its grading is determined by A, B or C. In some cases, there is even an AA rating, which is the highest. 

A - Best
B - Intermediate / Above Average
C - Satisfactory / Acceptable

Meanwhile, temperature refers to the heat resistance of the rubber material. This becomes more of a factor during long drives, in which the external elements, such as road tires and avoid low-resistant tires such as C, if the vehicle is always used for such a purpose.

A - Best
B - Intermediate
C - Satisfactory

Of course, there are other indicators to consider in proper tire and overall vehicle maintenance; but following even these basic ratings already equips the motorist ample information when choosing the right set of tires. It should not be about merely aesthetics, but more importantly, performance and safety should never be compromised.

It also important to note that tires also have a lifespan, and it is not just the tread level of your tires. Tires are exposed to different elements like UV rays and chemicals which may be on the road as you travel - these factors affect the life of your tires. Some manufacturers recommend a life span of up to 10 years for their tires, while some may recommend less. Best to check with the tire manufacturer as many local tire dealer sales representatives do not have sufficient information about tires.