We use a tyre so that the vehicle we drive would have a softer connection with the road. The tyres are attached around the outer edge of the wheels of our cars. Tyres are a big component which affects the performance of the vehicle. So here we talk about everything you need to know about tyres.
Tyre Condition affects the fuel mileage
So, what are tyres? Tyres are essentially rubber shoes for your car (filled with air/nitrogen). The primary material used to make tyres is rubber. These ring-shaped coverings are then filled with air. This is because air acts as a good buffer and absorbs shock from the road. The pneumatic tyre also reduces friction with the ground.
Construction of Car Tyres
Tyres may seem like simple and sturdy rubber disks. But there is so much detail that goes into the making of a tyre. It’s a complex engineering process that has a lot of physics and chemistry in it. Multiple layers made of multiple compounds work together to make the tyre run the way it does.
Different tyres perform differently. This is because there is a wide variation in the design of tyres. We need separate tyres for various functions. If we are classifying broadly, there are obvious variations in the design of passenger tyres, heavy-duty off-road tyres and others.
Depending on load and operating conditions, the components included in the tyre may vary. Compared to passenger tyres, heavier tyres like truck tyres may have additional ply layers, belt, breakers, or a heavier sidewall.
But more specifically, a lot of times tyres are designed as per the unique requirements of each car manufacturer and for each vehicle model. As each car runs differently, it makes sense that to optimize performance it needs to be paired with the right tyres.
Materials and Components
It’s not just rubber, an average tyre has. It has numerous compounds in the final product. Although, in most cases, other materials are used in combination with rubber for best results. Like an intricate dish, even the tiniest variation in the recipe can change the end product.
The base material used in the tyre is natural as well as synthetic rubber. Additionally, carbon black, silica, oils, sulfur, antioxidants, and so on are used as fillers. This is done right at the mixing stage to produce the sheets. As for other components, steel wire is covered in a rubber compound to form the bead. It is joined with the apex. Moreover, angled steel wires are used as breakers.
Firstly, the carcass of the tyre is assembled. The bead and apex are joined with inner liner and body ply layers, and finally with the sidewall. The sidewalls edges are then turned down mechanically to complete the basic carcass.
On a different assembly, we would have a belt drum. Here the belt is brought together, layering the ply with breakers, and then laying the tread. The belt assembly is then brought to the carcass and they are joined together. Compressed air is used for joining to ensure cohesion.
The final manufacturing step is cooking, or vulcanization if you prefer to be more civilized. The green tyre is placed in a patterned mould. The pattern is pressed into the tyre during the process. Rubber curing bladders are placed inside the tyre with high-pressure steam inside, that expands when the mould is closed. The process is done in high temperatures. For passenger tyres, it takes about 10-15 minutes. But heavier the tyre, the more time it would need. It may even go up to an entire day.
The tyres are removed after the required time. Like a baked bun out of the oven, they are then cooked and ready. Voila!
But before they hit the road, the tyres also need to go through rounds of quality inspection. Here the dimensional accuracy, surface uniformity, and so on, are checked and confirmed. It may be limited to visual and basic x-ray examination. Or it can include detailed lab tests and road tests.
Parts of the tyre
We saw how tyres are manufactured. Now let us look at the various parts that form the end product.
The tyre casing is comprised of everything except for the steel belts and the treads. But the plies, beads, inner liner and even the sidewall are a part of the casing.
The sidewall is the surface that makes up the sides. It is the portion on either plane, from the rim bead to the tread. The sidewall displays tyre markings referencing its size, load index, speed rating a.
Tyre Tread Check
This is the part of the tyre that comes in contact with the surface of the road. The tread has grooves and sipes that renders the required traction on the ground. However, the tread wears over time.
Sipes prevent skidding on icy roads
The tread patterns are also called grooves. We see these grooves in the tread of the tyre. The tyre can grip the road well, thanks to these grooves. Moreover, on wet roads, these grooves limit aquaplaning. The tread blocks also bear smaller channels or sipes that check skidding on icy roads.
The casing of the tyre has many layers that are composed of strings made of rubber-coated fabric. The fabric most commonly used here is polyester but we can find nylon or rayon in the plies as well. Plies in the tyre keeps the tyre in the required shape. They also make them stronger and more resistant to tread wear.
The tyre has belts that are essentially wires made up of steel. The rubber-coated steel wires are made into overlays that are placed around the tread of the tyre. The belts thus bolster the strength of the tyre.
Beads are the edge of the tyre that touches the rim. The rim on the other hand is the outer perimeter of the wheel. Consequently, the beads act as fasteners that make sure that the tyres stay fixed on the wheel. The beads too are also made of rubber-coated steel.
It is the edge of the tire where the sidewall meets the tread. Shoulder of the tyre is the part between the sidewall and the tread. The shoulder might carry treads that might look distinctive from the rest of tyre, but not always.
However, if the tyre loses pressure, the weight of the vehicle gets shifted to the edge of the tyre, that is to their shoulders. Shoulder wear can also be caused by over-inflation or bad suspension.
Which type of car tyre should you choose?
Automobile tyres come in different shapes and sizes. You would have decided which tyre would fit your requirements. Depending on what you use your car for and how you drive it the tyre you would need would differ. Besides the weather conditions would also dictate the kind of tyre you should choose. Different vehicles would also demand different tyres.
Your choice of tyres will also depend on whether you prefer a greater grip or stability on the road. If you want high-performance tyres, you can swap them out with ones you got from the manufacturer. Since tyres affect the performance of your car choose your tyres wisely. Here are some types of tyres.
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Maruti Suzuki Alto
They are made for normal weather conditions and provide greater traction on dry and wet roadways. These tyres have bigger tread blocks compared to other season tyres. Additionally, in rain, standard tyres have greater resistance toward hydroplaning. Hydroplaning happens when a layer of water gets trapped underneath the tyre.
Standard tyres are also called summer tyres. They are appropriately named so because they are no good if the temperature drops below seven-degree celsius. Nevertheless, compared to winter tyres, the performance of the summer tyres is inferior.
When you are driving in snow or ice, winter tyres are safer to use than standard tyres. In India, it is perpetually hot at least most parts of the country. Therefore, you can get away using standard tyres all throughout the year. But would have to invest in winter tyres, if you are living in the few colder parts, where snow and ice are common in winter.
Winter tyres use more silica compared to summer tyres. These tyres would give the vehicle a better footing on snow. Also, they have more tread pattern and sipes meaning a higher adhesion on wet pavements.
Wrangler Offroading | A/T tyres installed on SUVs do well in all terrains.
SUVs and other utility vehicles with four-wheel drive are often fitted with all-terrain tyres. All-terrain (A/T) tyres are good in the tarmac laden roads of the city. They also do well off-road, no matter what terrain they are driven on.
The elevated areas on the treads of the tyre are called lugs. A/T tyres have stouter lugs and hence they provide great friction.
Road Asphalt. Great for urban roads
These are premium tyres. Touring tyres are usually fitted on luxury cars. These tyres are great for the city road and often carry a speed rating of S or T. Besides they are not very noisy either. Many of these touring tyres also act as all-season tyres. It means you won’t have to switch out to winter tyres when December arrives.
They provide the greatest traction and road grip even when the vehicle is moving at top speeds. Performance tyres leave you feeling more settled even while making turns. They have plenty of tread patterns and are customarily outfitted on sports cars.
Tyres can also be classified as radial and diagonal based on how plies are laid one on top of the other. In radial tyres, plies are arranged to overlap each other, perpendicular to the direction of rotation of the tyre. Radial construction is most commonly found in tyres.
In diagonal tyres, plies are placed diagonally at a 55-degree angle to the central line of the tyre. The nylon cords are arranged diagonally in the tyre. They are also called bias tyres. Tyres with bias-ply are the best when the vehicle they are mounted on needs to carry a lot of heavy cargo.
Tyre Markings Explained
The sidewall is a repository of information about the tyre. When you need to buy new tyres for your car, do ensure that the car manufacturer’s requirements match with what the new tyre offers. Now let us look at all the markings present on the tyre.
Car Tyre Markings
The tyre size sequence
The most important marking on the sidewall of the tyre is the tyre size code. Here in the picture, the sequence that tells you about the dimensions of the tyre is 185/55R16. In many tyres, there would be alphabets LT or P engraved on the tyre before the code. LT and P stand for Light Truck and Passenger respectively. Application of the tyre tells you which vehicle it can be mounted on.
185: The width of the sidewall
The width of the sidewall of the tyre is given in millimetres. The tyre in the picture has a sidewall that is 185mm wide.
55: The aspect ratio
In order to find the sidewall height from the tyre markings, we would have to look at the aspect ratio. We can understand that 111.75mm is the height of the sidewall which is 55% of the tyre width (185mm).
R: Construction of the tyre
The tyre in the picture has radial construction. That is plies are arranged perpendicular to the axis of rotation. Most tyres have radial construction. Tyres also come with the alphabets B or D to denote its construction. B and D stand for Bias or Diagonal respectively. Tyres that have bias plies have layers of rubber-coated sheets placed at an angle to the axis of rotation. Therefore, by studying the tyre markings we can also understand how the tyre is constructed.
16: The rim diametre
It is exactly what it sounds like. The rim diameter is the diameter of the wheel the tyre is placed on. The rim diameter is given in inches. This Bridgestone’s Ecopia tyre in the picture should be on the wheel that has a diameter of no less than 16 inches.
Load Index and Speed Rating
These are usually given after that tyre size sequence. Here in the picture 83H denotes the tyre’s load index and speed rating. 83 is the load index or the maximum weight carrying ability of the tyre.
The maximum weight a vehicle can haul would be the 4 times the weight an individual tyre can lug. Since the load index here is 83 a single such tyre can carry 475 kg. Thus the car that has these Bridgestone tyres can lug 1900kg in total. Therefore, always remember to get the right tyre for your vehicle. When buying new tyres keep the load index in mind.
The speed rating is the maximum speed a tyre can handle. You should affix your car only the tyres that have a speed rating that is equal to or above the speed rating of your vehicle. Alphabets are used to denote the speed rating. Each alphabet corresponds to the maximum speed the tyre can handle. You can always check the car manual to know the kind of the tyre you would need to put in. Here in the picture, the H in 83H is the speed rating. The vehicle that has 83H tyres can go up to a speed of 210km/hr.
Similarly, here are some of the commonly seen alphabets that are used to speed rating. Each of the alphabets corresponds to a certain speed.
Additional Tyre Markings
Aside from the markings given above, your tyre can have other markings as well. Let us look at the others like the maximum load rating, maximum permissible inflation pressure, treadwear number and others.
Maximum Load Rating
In the picture, the maximum load rating of the tyre is 475kg. Load rating says the same thing the load index tells you. That is it is the utmost weight the tyre can bear.
Maximum Inflation Pressure
It is the maximum air pressure the tyre can withstand. But, you should not inflate the tyre to this point. This is because the ideal inflation pressure for your tyre will be lower. You will probably find it in the manual.
car tyre pressure information on door. Here you can see the manufacturer recommended inflation pressure
Higher the treadwear number the longer will it take for the tyres to wear out. However, the treadwear numbers would be brand specific. That is, we cannot expect the same performance from the tyres of two different brands with the same treadwear number.
Tyres are rated as AA, A, B or C according to the traction they exert on wet ground. Traction grade denotes how much would the tyre keep travelling even after you hit the brakes in rain. Greater traction implies faster halting.
Tyres with higher temperature grades can endure the most heat. Tyres that have a temperature grade of A won’t be damaged even at a higher temperature.
The year of manufacture
The tyre markings also tell you when it was made. We can understand the year of manufacture, as well as the week it was produced.
Your tyres will get damaged sooner than later. The tyre damage your vehicle can sustain can range from irregular wear to flats and bulges. First lets us look types of irregular tyre wear.
Center Tyre Wear
If you inflate your tyre more than necessary, the centres of the tyres are going to take the brunt of the damage. This means the centres would have more wear than the sides.
But the centre wears can also be caused due to other reasons as well. This can be attributed to the greater levels of torque produced during sudden acceleration. So this wear is a common sight in cars that have a relatively powerful engine.
Side Tyre Wear
Here it is underinflation that causes tread wear to concentrate on the sides and not the centre. Besides poor alignment can also be behind side wear.
Incorrect Tyre Inflation Affects Tyre Wear
A problem badly aligned wheels can cause your car is feathering. Here also the tyre becomes worn in an uneven manner. If you feel like the treads on the same tyre is worn smooth on one side but not so much on the other, this might be an indication of feathering.
Making turns at higher speeds can also result in feathering. Another reason to slow down we would say. Tyre damage from feathering can be prevented by rotating the tyres.
Heel and Toe Wear
Heel and toe wear can be spotted in the direction of the rotation of the tyre. This kind of wasting away takes place as a result of normal driving. Treads are thus worn out in the form of a heel and toe pattern. Heel and toe wear too can be fixed by rotating the tyres on a much regular basis.
Other Tyre Damages
Your tyre can also sustain punctures, cuts, bulges, cracks and other damages. Let’s look at some of these.
Punctures and Cuts
Your tyre can get punctured by debris on the road. Any sharp objects like pieces of glass, stones or a nail on the pavement can potentially give you a flat tyre. Cuts and tears too can be caused by sharper debris biting into your tyres. If driving over pothole results in cuts deep enough to expose the cords you should take your car to a mechanic right away.
Potholes | Inspect your tyres for cuts, if you run over a nasty pothole. It won’t hurt to check the wheel alignment too
Breaks and bulges
This can be spotted on the casing of the tyre. Breaks can be the result of hitting a harsher object on the tarmac. Additionally, if too much pressure is placed on the carcass of the tyre, the cords can break. Broken cords can result in a bulged sidewall.
Do not drive with a worn-out tyre
Most of the vehicles we see on the road have worn-out tyres. When we say worn-out tyre we mean the tyres that have most of their tread worn-off.
If the tread wear is down to 2/32 of an inch it is time to get new tyres. You can do the coin test to see if the tyre has tread wear. Place a coin in the groove of a tyre. If you can see the head of the Asoka Pillar, your tyre has sustained too much wear. Time to do something about it.
Driving with worn-out tyres is dangerous. Trust us when we say driving with a worn-out tyre can be outright dangerous. Here are some reasons.
Bald tyres are those that have almost all of their tread worn out. In bald and worn out tyres most of the surface of the tyre would come in contact with the road. This results in overheating.
Snow and Ice
Smaller grooves called sipes are responsible for good handling and traction on snow. But since they are absent in bald and worn-out tyres, tyres with a lot of wear are likely to make your commute during winter dangerous.
If the tyre has excessive wear it has a very big chance of getting punctured. This is because here most of the tread is gone making the tyre more exposed to the sharp debris on the tarmac.
The grooves on the tread channel the water underneath the tyre. Because of this, only a small amount of water gets trapped in the areas of the tyre that touches the road. But for a worn-out tyre, it is a different tale altogether. Since they do not have enough tread pattern left there is a chance of aquaplaning. Lesser traction on the ground increases the probability of skidding.
If you think your tyres are worn, go to a mechanic and get them changed, you know where to go!
How do you take care of your tyres?
You can use your tyre’s treadwear bar to check the wear on the tyre. If your tyre does not come with that, you can manually check the tread depth. Treadwear is a serious issue that needs to be addressed immediately. To take care of your tyres, make sure you drive slowly on bad roads. Don’t forget to drive slowly and carefully over speed bumps, potholes and debris on the road.
Also, monitor the air pressure of the tyre from time to time. You can check your car manual to figure out the right inflation pressure for your tyre. This is because if your tyre has low air pressure, more surface area of the tyre would come in contact with the road. As a result, the tyre could wear more quickly. Underinflation can also increase the chance of a blowout. On the other hand, overinflation exerts a lot of stress in the centre of the tyre. The centre of the tyre would swell and can wear out untimely. This means too much air pressure can cause the tyre to blowout as well.
Basic Car DIYs. Complete Tyre Guide | Tyre Rotation
Tyre rotation is very important and ensures an even wear on all the tyres. You can rotate your tyres after every 8000km or so. But how are the tyres rotated? Each tyre is taken off of its position and is put on the rim of another wheel. If your car has a rear-wheel drive, you can remove the front-right tyre and place it on the rear-left wheel. By using the cross pattern you can rotate the other two as well. If you rotate your tyres you can save a couple of trips to store to get new ones.
Another way to make the tyres wear evenly is by balancing. Balancing makes sure that the weight allowance around the car is even. If you feel some irregular vibrations you should go to the service centre to get your tyres balanced.
Tyre balancing is done using a balancing machine. Any imbalance is fixed by adding weights. The tyres would then travel smoothly and evenly once you balance them.
Complete Tyre Guide
You don’t have to align your wheel as frequently as you rotate or balance them. Wheel alignment is fixing the angle of the wheel so that the car can run straight. Here we tweak the car’s suspension for correcting the angle the tyre makes with the road. You can take your car to your trusted service centre if:
- The steering wheel produces noise and vibrations. And it feels heavy when it should not.
- You can’t make the car travel straight. That is you feel like the car is pulling you to either side.
- If the wheels are poorly aligned your mechanic can easily fix them.
5 Dos and Don’ts with Tyres
Let us wind this up with some things you should do and don’t do when it comes to your tyres.
You should do this!
Wait till the tyres are cold
When you need to check the tyre pressure, you should not do it hot tyres. Only check the tyre pressure on cold tyres. Additionally buy a pressure gauge if you don’t have one.
Check the wheel alignment
Make sure your car wheels are aligned the way your manufacturer wants you to keep. If you run over a speed bump or any irregularities in the road that is likely to throw off your wheel alignment take the time to check it.
Buy good quality tyres
Poor quality tyres will puncture sooner. Besides they will also wear down faster. This means you would have to get them replaced often. And at the end of the day, you will spend more money if you go with the cheaper option.
Carry around a tyre repair kit
If you have a patch repair kit handy any puncturers your tyre could sustain might become less of a headache. You can fix perforations on the spot before it becomes worse.
Book a tyre service
You can book a tyre service as frequently as necessary.
Carry a spare tyre
Always have a good spare tyre. When a time comes when you need to use it, don’t forget to get a new spare tyre to take its place.
Don’t do this!
Don’t use tyres lower speed rating compared to your vehicle
Know the speed rating and load index of the vehicle tyre. And always remember to use the tyres ones that suit the vehicle you drive.
Don’t use tyres that are too big or small
You can find the tyre size sequence on the sidewall of the tyre. You should remember to match the tyre size with the tyre size specified by the manufacturer. Using tyres that are not the right size can be dangerous.
Don’t speed on wet roads
Rains mean more motor accidents. And wet roads mean more hydroplaning. Thus the traction of your vehicle can go down on wet roads.
Don’t pull out a nail stuck on the tyre
If your tyre picks up any sharp object from the road, don’t pull it out of the tyre yourself. Go to a mechanic to get the tyre fixed and restored.
Don’t drive on bad roads
Unpaved or pot-hole filled roads can wear out the tyres sooner. This means we would have to get new tyres sooner or retread old ones.
This concludes this piece on everything you need to know about tyres. We hope you apply what you learnt and good luck with your tyres!
Source: Kavitha Nambiar (Geomechanic)