Know Your Tyre

Everyone knows that the engine is the most important component of any modern-day vehicle. But, if you really want to think about it, a car with even the most powerful and most efficient engine will still not be able to bring you to your destination without your car’s wheels and the tyres that are mounted onto the wheels. Technically, your tyres are what connect your car to the ground. Such is the importance of tyres that we’ve prepared this ultimate guide to help you better understand that piece of technology that keeps you rolling wherever you may want to go.

Different Types of Car Tyres:

Like everything else in this world, different things come in various types or kinds. The same is true with your car’s tyres. Choosing the right tyre to mount onto your car’s wheels is dependent on several factors including the general use of the vehicle and driving conditions, among others.

If you are the type of driver who would love to take it slow as you ease down into each corner of the road, then you will need a different kind of tyre than someone who considers himself an Ayrton Senna-incarnate who would really love pushing the nose of his car towards the apex to make that beautiful turn. Your driving behavior will dictate what kind of tyre you should put into your car. If you’re a real F1 racer, you can forget those tyres with treads because you’d want the largest contact patch on the tarmac. If you’re a rally racer, you cannot put F1 slick tyres onto your wheels or else you risk flying through the thick forest and into the trees. If you’re a drifter, then a different set of tyres will again be required. As such, one of the major factors in choosing the type of car tyre to buy is related to how you use your car.

As we have already mentioned above, an F1 racer’s tyres will be different from someone competing in the WRC or even someone who takes his car through gridlock after gridlock of traffic on city streets. The point is that driving conditions will also dictate what kind of tyre you need to put in. For instance, if it’s snowing, then you’d need tires with large and deep treads to help you move your vehicle through the snow. They also have miniscule metal studs that are embedded into the tread to help the tyres bite into ice and snow.

One of the inherent characteristics of a good ride is diving comfort. You should be able to drive over obstacles with very minimal vibrations from the road. But did you know that your choice of a tyre can have an effect on the noise that is generated by the tread patterns?

Now that we’ve seen some of the things that can affect your decision to purchase a certain type of car tyre, let us now focus our attention to the different types of car tyres.

Summer or performance tyres:

That F1 racing slick we mentioned above rightfully belongs to this class of tyres. If there is one thing that defines this class, it’s speed. And whenever speed is involved, grip is the key. You simply cannot go really fast without getting airborne. As such, the tires need to have as much grip on the ground as they possibly can. These are made of soft rubber compounds and come with very minimal tread block patterns to none at all. For performance tyres, to hell with mileage. What matters is the tyres can ensure performance and grip.

All-season or all-around tyre:

Every modern car that rolls out of the assembly line is equipped with a set of all-around or all-season tyres. These provide you with the right balance of performance, grip, wet-weather safety, acceptable noise, and durability. These are constructed of harder rubber compounds that have a negative impact on cornering performance and grip. It really is not an issue, we think, since 9 out of 10 motorists are essentially driving their cars with these tyres on. These also have an excellent compromise between water dispersion and quiet running. These work pretty well on wet roads and on heavy downpours. Running with these tyres won’t give you that dreaded noise when driving, too

Wet weather tyres:

If you’ve got summer tyres, then you definitely have wet weather tyres, too. You might think that these will be constructed of harder rubber compounds than those found in all-season tyres. On the contrary, these are a lot closer in composition to performance tyres, albeit softer. Another major difference from performance of summer tyres is that wet weather compounds come with substantially more sipes to help channel water away from the tyre’s contact patch. Here’s the thing: tyres during the rainy season should be able to heat up quickly so that their contact with the road surface will be ensured. That is why it has a much wider contact patch than an all-season which makes it a lot closer to a performance compound. It should also be able to channel water away so it has to have the sipes of the all-season.

Winter tyres: snow and mud or snow and ice:

Driving in the winter can be especially challenging. Putting on the wrong set of compounds on your car is always a recipe for disaster. That’s where aset of the best winter tires come in. There are two types of winter compounds, depending on the prevailing environmental conditions in your locality. If you’ll be driving mostly on snow and mud, then you’d find M&S tyres to be especially helpful. If you’ll be driving mostly on snow and icy roads, then winter tyres with the snowflake symbol are your best bet. These tyres have larger block patterns to allow for optimum contact with the snowy, icy, or muddy surface. Many have metal studs embedded into their treads which help improve grip especially when driving over icy roads. Unfortunately, these come with a very noisy downside.

All-terrain tyres:

If you’re driving a light truck or even an SUV, then an all terrain tire is for you. These have very stiff sidewalls, allowing them to roll over rocks and other obstacles in mostly unforgiving roads. They also have larger tread block patterns, allowing them to grip dirt, gravel, and even loose sand. Unfortunately, because of the large tread blocks, you can expect these rollers to be noisier and offer less contact surface on paved roads. As such, you really cannot expect to go really fast on highways without risking slipping or even flipping over. When it comes to hardness, all terrain tyres are in the middle; not soft, not hard.

Mud tyres:

You can look at these compounds as a subtype of all-terrain tyres. The tread block patterns of these compounds are massive, very chunky. Under no circumstance should you take these rubbers on any other surface except mud and dirt. In some cases, the tread blocks don’t look like blocks at all; they resemble chunky paddles.

Tyre Construction:

The different types of compounds underscore the different types of tyre construction. We did mention something about tyres having soft and hard rubber compounds as well as those with tread patterns of various sizes and designs. The thing is that the way by which a tyre is constructed can have a significant impact on its overall performance; whether it is built for speed or for optimum driving comfort or for navigating over treacherous terrain such as mud, snow, ice, loose sand, and rocks. It is thus important that we take a look at how tyres are constructed.

There are essentially two types of tyre construction: cross-ply and radial.

Radial:

Majority of modern vehicles have the radial system on their wheels because it provides exceptional cut resistance on the tread, superior traction, heat and wear resistance, flotation, and, above all, better fuel economy.

Cross-ply:

Just because majority of modern vehicles sport the radial tyre doesn’t mean that cross-ply tyre construction sucks. When it comes to sidewall cut-resistance, you’ll see later on that it is exceptional. It is also very easy to repair and has this amazing property of self-cleaning. Perhaps, the most intriguing advantage of a cross-ply tyre is the level of stability and steadiness it affords the vehicle.

Now, let us try to look at the different parts that make up these two types of tyre construction.

Tread:

This part of a tyre is designed to transmit forces between the road surface and the tyre. It is made of vulcanized or specially compounded rubber material that should be able to resist wear, cut, heat, and low rolling in varying degrees. Some modern compounds already combine these resistance capabilities to afford the tyre of exceptional performance in various driving conditions.

Sidewall:

The sidewall of the compound is especially designed to resist weather checking, scuffing, cracking, and cutting. It is usually constructed of rubber that protects and coats the outer side of the tyre, hence the name sidewall.

Chafer:

In cross-ply tyres, the chafer is what protects the body and the bead from chafing. It is located in the area where the compound gets into contact with the wheel or the rim. In radial tyres, the chafer serves more as reinforcement to the bead by increasing its overall stiffness. This leads to increased bead durability. Essentially, radial tyre chafers transform the torque forces that are applied by the wheels to the ply of the radial tyre. It also helps prevent deformation and deflection of the bead.

Liner:

If you have a tubeless tyre, then it should have a liner covering the inside surface to help prevent air from leaking or escaping.

Bead:

This is the foundation of all tyres. On a cross-ply system, the bead is composed of two to three bundles of high tensile strength steel wires that have been coated in bronze and insulated with rubber. On a radial tyre, there is only one bundle of these bronze-coated steel wire strands.

Cord body or body ply:

Cord body or body ply is what technically keeps the pressure within the tyre itself. Cross-ply tyres have the cord body which is typically composed of several layers of nylon plies. Each ply comes with nylon cords which are individually wrapped in resilient rubber. The nylon cords run diagonally with respect to the direction of motion. What these cords do is transmit the forces generated by the tread to the bead. The cord body is what absorbs shocks while driving as well as supports the load on the tyres.

If the cord body is for cross-ply systems, then the body ply is for radial systems. This is essentially composed of a single layer of stronger steel cord wire which runs laterally from bead to bead in the direction of motion. It is for this reason that it is called ‘radial’. The function of the body ply is similar to the cord body – confines the pressure within the tyre and transmits torsional and torque forces to the bead and to the rim.

Breaker or belt:

Breakers protect the cord body in cross-ply systems against cuts while also increasing the overall stability of the tread. These are often constructed of nylon, steel wire, or even aralon. The equivalent of the breaker on radial systems is the belt. While breakers can be made of any of several materials, the belt is usually made of steel cord wires arranged in several layers between the body ply and the tread. Road tyres will have one or two layers of these steel cord wires while off-road compounds have 4 to 5. The radial belt increases tread rigidity and thus, cut resistance. Belts also transmit forces to the body ply while restricting tyre growth. This helps prevent cutting, cracking, and the growth of the cut.

Tread Patterns:

One of the most important considerations in the choice of the right tyre for any vehicle is the tread pattern since this can have an impact in traction, handling, and durability. Choosing the right tread pattern for your vehicle also helps in improving ride comfort, reducing noise levels, and plays a role in improving fuel efficiency. Currently, there are three patterns of treads in modern tyres. These are as follows:

Symmetrical:

In this type of tread pattern, the treads on the tyres typically follow a uniform design. If you were to cut the tyre lengthwise along the grain of the tread so that you have two complete tyres, right and left, both of these halves will have exactly the same tread design. That is why it is called as symmetrical tread pattern.

Asymmetrical:

Going back to our two halves, one of the halves will have an entirely different tread pattern when compared to the other half. Normally, these types of tyres have larger tread blocks integrated into the outer portion of the compound. This is to help make sure the tyres remain relatively stable especially when cornering. The inner sections of the tyre come with smaller tread blocks as well as the inclusion of more water-channeling grooves. These grooves also serve to dissipate heat from the rubber compound.

Unidirectional:

These types of tyres are specially fitted on vehicles that require acceleration on a straight line. On the superficial side of things, you might think that they resemble symmetrical tread patterns since if you halve the tyre, a halve will typically contain the same design as the other halve. But there is actually a unique feature in unidirectional tyres. These are especially engineered to turn in only one direction. It is crucial to mount such tyres on your rim following the direction of the arrow marked onto the sidewall of the tyre.

Remember to keep this in mind since putting it in the wrong way can have serious consequences. Aside from greater acceleration because of a reduction in rolling resistance, such types of tread patterns also allow for a shorter stopping distance, making them especially valuable among racers as both acceleration and stopping distances can help define race performance.

Tyre Sizes, Markings, and Profiles:

Take a look at your car’s compounds and you’ll see several markings, typically a combination of numbers and letters. Here’s how you can decipher all the information without necessarily getting a headache.

Tyre size:

This is one of the most important markings since it gives you an idea of the size of your tyre and, with it, the size of the rim.

Let us have an example: 185 65 H R 13

In this example we have 5 sets of data.

  • 185 is the width of your tyre, measured in millimeters
  • 65 is the aspect ratio of the sidewall, expressed in percent. As such, this means this tyre has a section height of 65% or 185 which is 120.25 millimeters. This is also known as the tyre’s profile.
  • H refers to the speed rating of your tyre
  • R is the type of tyre construction; it’s R so it means radial
  • 13 is the diameter of the rim; oddly enough this is in imperial measurement, in inches to be exact. As such, you have to convert this into millimeters if you’re considering on up- or down-sizing your rims and tyres.

Other markings:

Aside from the tyre size and aspect ratio or tyre profile, you will also see a variety of other markings on your tyre. These can include the following

  • Name of the tyre including the manufacturer, brand, or any other commercial identification
  • Type of tyre construction
  • Tyre pressure requirement (You may also like our review of the best tire pressure gauges)
  • ECE type approval
  • Compliance symbols as well as ID numbers from the North American Department of Transport
  • The country where the tyre is manufactured
  • Temperature rating with “A” as the highest and “C” the lowest
  • Traction rating with “AA” as the highest and “C” as the lowest
  • Tread wear rating
  • DOT code as well as the mandatory 6-year shelf life of tyres.

There may be other markings on your tyre. For instance, if you are still running classic vintage cars, you’ll find tire size markings to be in inches. As such, you’ll see 7.6×15 instead of a 195/100R15. Regardless, it’s all a matter of converting inches into millimeters.

How to Check Your Tyres for Wear:

It should be fairly obvious by now that the integrity of your tyres can spell safety on the road. That is why part of your routine vehicle maintenance checks is to make sure that you have a set of compounds that can maintain excellent contact with the road, allow for efficient manoeuvring, and prevent hydroplaning. Here are some things you need to look for when checking the integrity of your compounds.

Shoulder wear:

In this scenario both shoulders of your tyre show signs of wear a lot faster than the center. This can be caused by underinflation, tyres that have not been rotated, improper matching of the wheels or rims and the tyres, and repeated cornering at high speeds.

Center wear:

If the center of the tyre is the one that is showing signs of wear, this is often an indication of over-inflation. It can also mean that you did not properly match the tyre to your rim or it could also be that you have forgotten to rotate your tyres in the recommended frequency.

One-sided wear:

If only one shoulder or side is showing signs of wear this is often indicative of improper camber alignment. Or, as we have said earlier, it could very well be the result of failing to rotate your tyres.

Spot wear:

If the wear occurs only in one spot or section of the tyre, this is called a spot wear. It can be brought about by faulty suspension, faulty brake components, or faulty rotating parts. It can also be due to a dynamic imbalance in the tyre and rim assembly or even an excessive runout of this assembly. Underinflation could also bring about spot wear as well as rapid starts and sudden stops.

Diagonal wear:

Not to be confused with spot wear, diagonal wear typically occurs on tread components, usually following a diagonal pattern. The causes are somewhat similar to having spot wear although improper wheel alignment and failure to rotate the tyres are fairly common.

Feather-edged wear:

If you see the ribs or the tread block forming a feather-edged pattern of wear, this is often an indication of a faulty toe-in in your wheel alignment. It could also be because of a bent axle beam.

Tread wear:

This is quite easy to check since modern car tyres now have tread wear indicators built-in. A bar of rubber is molded right into the tread rubber usually at a depth of 2 millimeters. If your tires tread becomes flush with the rubber bar indicator it simply means you now need to change your tyres as you’ve already used up about 2 millimeters worth of rubber.

Rotating Tyres:

One of the most common reasons for uneven wear in tyres is the failure to rotate the tires in a regular manner. Don’t be confused by the term “rotating” as it has nothing to do with physically moving the tyre in the axis of its wheels. Rotating tyres simply means swapping the front and rear rubbers to make sure that wear is even. As a general rule, you need to rotate your tyres after every 5,000 miles even though there are no signs of wear. Here’s a quick rundown of how to rotate your compounds depending on the system present in your car.

  • For front-wheel drives with non-unidirectional tyres, the front can be swapped with the rear on the same side while the rear should be moved up front on the opposing side. For example, swap the right front tyre with the right rear tyre. The right rear tyre will swap with the left front tyre.
  • For rear-wheel drives with non-unidirectional tyres, you can swap the tyres using the same principle as in front-wheel drives with non-unidirectional tyres except that the front tyres need to be swapped with the rear tyres on the opposite side of the vehicle. So, swap the right front tyre with the left rear tyre. The rear tyres swap directly with the front tyres on the same side.
  • For 4WD with non-unidirectional tyres, you can swap both front and rear tyres with the tyres on the opposing side. So, right front tyre swaps with left rear tyre and left front tyre swaps with right rear tyre.
  • For unidirectional tyres, swapping occurs on the same side. This means front and rear tyres can only be swapped with the tyre on the same side. For example, right front with right rear or left front with left rear.

Your car’s overall safety especially on the road is dependent on a variety of factors. However, since it is actually your tyres that are in constant contact with the road surface, it is important to keep these rotating rubber compounds in top shape. Understanding the different types of car tyres including their construction and tread patterns as well as the different markings on their sidewalls can help pave the way to better appreciation of the importance of this integral part of any modern vehicle.

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