EVERYTHING YOU NEED TO KNOW ABOUT TIRES 

Tire technology was evolving like any industry. Today they constitute true engineering developments obtained from sophisticated research and testing laboratories, and several hours of tests on closed tracks where they are tested under controlled conditions of temperature and time.

Understanding the specificity of each tire allows you to make the best purchase decisions and understand the vital importance of proper use and correct selection.

The tires vary according to the use or the vehicle to be equipped. Although the structure includes common materials, its composition varies to prioritize a particular service.

There are natural and synthetic rubber tires (derived from petroleum), whose materials are found in a greater proportion in the tread. These materials are responsible for suffering abrasive wear when in contact with the ground. Be it acceleration, braking and / or cornering. To these materials are added different meshes of textile and steel fibers, which give flexibility and rigidity to the structure. The steel meshes are basically found along the entire tread, while the textiles cover the entire interior of the tire. The steel also provides greater rigidity at the bead height, where it is anchored to the rim. This prevents the tire from coming off or slackening.

The carbon black gives the tire color, and mixed with the rubber using mechanical extruders it provides mechanical resistance to abrasion suffered by the constant rubbing against the floor. They also incorporate other minerals such as sulfur and zinc oxide or silicones that provide specific properties for heat dissipation or use on ice and snow.

That said, the most quickly visible features are measurements. The dimensions of a tire are detailed on the side and are made up of three elements: width, height and diameter. To understand it, we are going to give an example: suppose that our vehicle is fitted with 195/60 R15 wheels. The first number indicates the tread (that is, the width or the tread) in millimeters; So, for example, in our example, the 195 tells us that it is 19.5 cm wide.

The second speaks of the profile or height of the roof; in this case it is 60. But that 60 does not correspond to its height in millimeters but to the percentage of width. So this tire will have a height of 11.7cm (that's 60% of 19.5cm). Hence it follows that the lower the ratio, the lower the flank or side.

The letter R indicates that it is a radial tire (there are almost no other types) and refers to the way in which the textile and metallic fibers are placed at the time of manufacture. Finally, we have the number 15 that indicates the internal diameter of the tire expressed in inches; or what is the same, the diameter of the rim. In this regard, it is good to clarify that each vehicle leaves the automotive terminal with the specific tire size for that model, and that if you want to install wider, lower wheels, etc., they must be reviewed or adapted to other systems (brakes, cushioning and more) so that they continue to provide safety in the ride.

Then other numbers appear (usually 75 to 100) accompanied by a letter (from A to Y, plus VR and ZR, with the H placed between U and V). The numbers respond to a coefficient and establish the maximum load in kilos that each wheel can bear; for example, 80 is 450 kg; 90 is 600 kg, and 100, 800 kg. Meanwhile, the letter indicates the maximum speed index for those that were approved to be used safely and with maximum load. Some examples: J equals 100 km / h, N is 140 km / h and U is 200 km / h. These indicators are important since, on the one hand, if the wheels that carry loads higher than the maximum approved can become overheated, which can cause their destruction. And, on the other hand, at high speeds the tires are more likely to be damaged by road hazards or accumulated heat, just as it can also cause rapid loss of air or even a sudden explosion.

When describing the tire, the profile was mentioned. In that sense, there are two types: low and high, each of which has its advantages and disadvantages. Low-profile ones tend to be wider than regular ones and also have larger edges. This means that they have a greater contact surface with the ground and, therefore, a better grip (especially when cornering). This feature makes them ideal for use at high speeds and also helps in the event of sudden braking on a dry surface as there will be more surface in contact with the ground to help stop the vehicle.

In contrast, by having more contact surface they produce greater resistance to advance, which translates into greater fuel consumption. In addition, the larger support surface makes them copy more the imperfections of the terrain which implies a lower ride comfort since to avoid this, harder shock absorbers must be fitted; in short: more harshness in walking. Finally, when driving on wet terrain, the greater width means that the water does not drain quickly from the tire and can generate the dreaded hydroplaning effect.

The high-profile ones, meanwhile, offer a smoother and more cushioned ride (due to having a greater inflated surface), lower fuel consumption (the smaller tread generates less contact with the pavement and, therefore, a less need for power to move the car) and better braking on wet surfaces (the treads allow the water to evacuate more quickly).

Each manufacturer provides its tires with particular patterns or grooves. These are directly related to the grip they are going to offer, since these grooves allow a better grip on dry floors and the exit of water on wet floors. And they all follow three fundamental parameters:

Symmetrical drawing: they are the most common and the best for normal vehicles. If the tire were divided in two longitudinally, they would have the same patterns on both the inside and the outside. They are characterized by offering a smooth ride, great ride comfort, high directional stability and low rolling resistance (they wear less). They are ideal for dry floors.

Asymmetric tread: they are designed for sports or high performance cars. They have different drawings on each side and are made with different materials and reinforcements in certain areas. The inner side tread has more grooves and seeks to avoid aquaplanning, while the exterior is designed to provide greater grip in curves (it is in these circumstances that this part of the tire is required).

Directional tread: they are ideal for driving on low-grip surfaces (rainy areas, snow) as they offer a lot of grip and good braking. They have arrows that indicate the forward roll direction, and must be mounted to be used exclusively in that direction.

FOR EACH TERRAIN

This aspect is especially related to double contraction vehicles, integral or pickups, since they are the ones that usually move through different types of terrain. There are three variants:

High Terrain (H / T, paved terrain): designed specifically for driving on asphalt and are ideal for those vehicles that move in the city, road or highway, as they offer low wear and a long service life.

All Terrain (A / T, mixed use): designed to be used both on asphalt and on terrain where better traction and grip are needed. The material used for production is much denser to prevent the vehicle from skidding in case of wet or damp terrain and to provide greater resistance to cuts and impacts.

Mud Terrain (M / T, Unpaved Terrain): Used on uneven surfaces, areas of deep mud, or areas with slopes. They offer excellent resistance to tears and, thanks to the wider channels in their pattern, mud cannot be trapped, thus increasing the grip surface.

THE TEMPERATURE FACTOR

There are also tires designed for specific weather conditions. In this sense, you can find those designed for summer, winter or any season.

The former are prepared to perform in wet and dry conditions, providing grip and control thanks to the specially designed pattern for the correct expulsion of water. On the other hand, they absorb the lateral stresses produced by walking, which allows to enjoy a much more comfortable driving experience in the conditions mentioned above.

The winter ones should be used if you live in areas with regular temperatures below 7 ° as they are designed to provide grip, traction and control on very cold surfaces and with water, snow or ice. This is because the product's compounds remain soft and flexible despite low temperatures, resulting in better braking power and greater maneuverability. Unlike a standard tire, those for winter use are identified because they have symbols on their side (three mountain peaks, a snowflake) and the initials M + S (Mud + Snow, that is, mud and snow).

But to avoid changing tires when going from one station to the other there are so-called allseason or allweather. They are designed for comfort, control and good traction all year round. They generally feature an asymmetrical tread pattern along with circumferential grooves to optimize grip in wet weather.

EXPIRATION

According to experts, "tires do not expire or have an expiration date and their useful life depends mainly on their conditions of use." The DOT (Department Of Transportation) factor that appears on them corresponds to the date of manufacture and is not directly related to the age of the tire.

This DOT is made up of four figures that indicate the week of manufacture and the year; for example, if it says 5420, it means that it was produced in week 54 of 2020. But what does matter when calculating the age of the tire is its assembly date, since its useful life begins when it begins to roll. Therefore, it is only after 5 years of running that they must undergo a thorough review by a specialist to determine if it is necessary to change them. After 10 years, some brands recommend replacing them regardless of mileage, visual appearance or maintenance.

THE TIRE PRESSURE

Tires lose up to 1 psi (pound per square inch) per month, so all tires (even the spare) need to be checked every 30 days and especially before a long trip. The measurement should be done cold, before driving or at least three hours after the vehicle has been used. The inflation pressure has a direct influence on their useful life, because if they are over inflated they will not wear evenly and will not last long. On the other hand, if they are low they will consume more fuel. The correct pressure is reported by the vehicle manufacturer and can be found in the car manual, on one of the front door posts or on the fuel tank cap.

CHECKS AND REPLACEMENTS

The life of a tire depends on a combination of factors such as design, driver habits, weather, road conditions and how they are cared for. But to know what condition they are in, you have to check them periodically and identify possible problems. What is there to check?

The depth of the drawings, which should not be less than 1.6 mm. To check it, there are the wear indicators (called Tread Wear Indicator, TWI) found in the tread (small perpendicular or diagonal grooves between the main grooves). Once they reach this mark they must be replaced.

• If you have signs of uneven tread wear. If so, a rotation may be necessary.
  
• If there are foreign objects in the drawing (stones, nails, etc.). Take them out and check that they have not damaged the rubber.
  
• If they present damages, cuts, balloons, deformations and other anomalies.
  
• If any of the above situations occur, it is recommended to replace them.
  

Also pay attention to the "feel" you have when driving, as an uncomfortable ride can indicate damage or excessive wear. If vibrations or other disturbances are noticed, slow down, drive carefully until the road can be safely exited, stop, and inspect the wheels.

If a tire is damaged, it will need to be deflated and replaced with a spare. If no damage is observed and the source of the vibration cannot be identified, it is recommended that the vehicle be taken to a service center for a thorough inspection.

ROTATE THEM, HOW?

Finally, it is important to know that the tires must be rotated because the front and rear axles wear the tires differently. How do you do it? The tires that were on the front axle are placed on the rear axle (keeping the same side of the vehicle) and vice versa. However, there are specific situations where a cross rotation is recommended, in X, moving the right front tire to the left rear position; and vice versa. Therefore, it is necessary for a specialist to check the type of wear to decide which is better.

The rotation must be carried out preventively on average every 10,000 km traveled.

vs Oct 2021