Tyre Basics
Tyres are all that is connecting your car with the road. They keep you safe and they improve the performance of your vehicle.
Yet their importance is often overlooked. While all tyres are made from rubber, there are major and more subtle contrasts between brands and tyres.
What’s Important in a Tyre
It’s easy to see the differences between vehicles. A Mitsubishi Lancer has little in common with a Nissan Altima or a BMW 3 Series. But while everyone can quickly visualise the contrasts between vehicles, the differences between tyres are not always obvious.
Unfortunately, tyre technology is not straightforward. Tyre manufacturers have adopted an international standard of terminology – many of these terms can seem like a foreign language at first. Fortunately, you don’t need to be an expert to buy a tyre. The best place to start is knowing the questions to ask.
Certain features are essential to the performance and safety of a tyre. They will also tell you if the tyre is suitable for your vehicle. Understanding these important features is the best way to feel informed when purchasing.
Tyres are graded using a uniformed system that has been adopted in most of the world. This system allows you to compare tyres objectively and select the one that is best suited to your vehicle.
Treadwear: This rating is an indication of how durable the rubber and tread on the tyre are. The higher the number the longer the tyre will last. For example, tyres rated at 420 will potentially last twice the time as those at 200. If you’re regularly driving off road or seeking extended durability then look for tyres with a rating of 300 or more because off-road driving causes more impact and wear; a rating of 700 is outstanding. The exact amount of time your tyres can last is also based on how often you check your tyres and how you care for your tyres.
Traction: This grade tells you about a tyre’s ability to stop. Grade AA is the highest and grace C is the lowest. If you like to drive fast or like to maximise the safety of your vehicle, look for tyres with the high grades.
Temperature: Tyres get hot when you are driving, especially when you are driving for long distances or at high speeds. The temperature rating shows how resistant the tyre is to these high temperatures. Grade A is the highest and grade C is the lowest that should be considered. This temperature rating is very important in the Middle East, particularly in summer, when the baking roads and high air temperature put more pressure on your tyres.
When purchasing a tyre in the Middle East, the size you want will depend on the car you drive. However, many different sizes of tyre will fit your vehicle and you should not feel restricted to an exact size.
Tyre size can seem confusing. 185/70R14? 225/65R16?
This visual talks you through it in four steps:
1Rim Size: This is the diameter of the vehicle rim, measured in inches. The size of the tyre must match the size of your rim. So if you have a 16-inch rim then you must buy 16-inch tyres.
2Width: This is the width of the tyre, measured in millimetres. For example, 205.
3Profile: This is the depth of the tyre and is expressed as a percentage of the width. If your tyre size is 205/50 then the depth of the tyre will be 102.5 millimetres (50 percent of the width which is 205mm).
4Load Index and Speed Rating: These figures are not related to the size of the tyre and are explained later in this article.
If you are not sure, remember that tyre dealerships are experts in tyres. They will help you understand what these figures mean and will only recommend tyres that fit your vehicle.
The tyre speed rating shows the maximum speed you can drive with the tyre. You must use tyres that match your vehicle’s top speed. However, buying a tyre with a speed rating that far exceeds your car’s top speed means spending more money for no benefit. Most tyres have a tyre speed rating that reflects how they are used. For example, performance tyres for sportier saloon vehicles should have a higher tyre rating, such as V – Y. Tyres for SUVs will be lower, maybe S or T, as the technology in the tyre focuses more on durability and stability.
The tread design impacts how the tyre performs in different conditions and on different surfaces. For a quiet and smooth drive on the road, look for a variable pitch tread design. If you’re driving off road, then deep stair-step tread grooves help to navigate the terrain.
Many tyres have a standard tread design. Some tyres have a specially-designed tread design. Whether the features are important will depend on your vehicle and where you drive. For example, many big-brand tyres have special features for regular driving on wet roads. Different features become more important when you are driving on dry and hot roads.
All tyres should come with a warranty, just like any electronics item you buy from a store.
The longer the warranty the more confidence you can have in the tyre. Remember to ask about the warranty when buying your tyres. But also ask the dealership what you should do if there is a problem with a tyre.
Is there a local number to call for assistance? Is there a local support network or a technical team that can solve your problem?
Understanding More Tyre Terminology
Many drivers will not need to know any more than the basics of what is important in a tyre. Any tyre dealership can assist you with the more advanced terminology. But to really makes an informed decision, you may want to ask more complicated questions.
Each aspect of the tread design has a purpose. When a tyre has a unique tread design it mixes additional features to improve the safety and performance of your drive. There is no ultimate combination of these features and many of the features have a similar purpose.
Shoulder Grooves – Helps to reduce running noise.
Ladder-Like Grooves – Improves stability when going off road.
Pattern Grooves – Offers superior braking force.
Circumferential Grooves – Enhances grip and stability with larger loads.
Circumferential Grooves – Enhances grip and stability with larger loads.
Variable Groove Shoulder – Reduces shock, especially off the road.
Asymmetrical Pattern Design – Provides strong grip.
Continuous Pattern Blocks – Increases stability.
Stair-step Tread Grooves – Minimises stone retention.
The Load Index (LI) rating follows an international standard. It determines how much weight each tyre is capable of carrying. Fitting a tyre with a Load Index that is too low will compromise on safety. It makes sense that a 20-inch tyre can carry more weight than a 13-inch tyre. But every size of tyre can come with a different Load Index rating. Your vehicle manual will include details on the recommended Load Index rating for your vehicle. If in doubt, always buy new tyres with the same or higher Load Index rating than your existing tyres.
Load Index is printed on every tyre. You can use the table below to calculate the load in kilograms. Remember that Load Index refers to the weight each tyre can carry. A LI score of 98 means each tyre can carry 750kg. That means a total of 1500kg spread over the axle when the weight is distributed evenly (750 x 2 tyres on the axle).
Some tyres have been specially reinforced to carry more weight. This is indicated with the XL acronym. These tyres are naturally more expensive because of the technology and materials that make the tyre stronger. XL tyres are commonly required when you are carrying more passengers – for example if you drive a saloon car with more than five seats.
XL is an immediate indication that the tyre is reinforced. However, this improved capability is already reflected in the Load Index rating. So XL does not mean the tyre can carry extra weight beyond the Load Index rating.
The maximum width of the tyre at its widest point. This is measured from the inner sidewall to the outer sidewall when there is no load placed on the tyre – i.e. not when it is fitted to a vehicle. Section width is measures in millimetres.
Rim size is the starting point for selecting a tyre and refers to the diameter of your rim. Each tyre also has a standard rim width measurement
Tyres are manufactured to fit on many vehicles and absorb the impact of many conditions. Because their sidewalls are flexible, the same tyre can fit on rims with different widths. But, of course, a single tyre can only fit on one rim diameter size.
Standard rim width is measured in inches. The figure shown in the tyre specifications refers to the ideal rim width for the tyre. You will also be able to fit the tyre on a rim that is slightly wider or narrower.
This is a vertical measurement, from the surface of the tyre to the bottom of the tyre’s deepest grooves. Tyres will naturally wear over time, so the groove depth will decrease as rubber is worn off the tyre.
Blacklion presents groove depth measurements in millimetres.
The legal minimum limit for tyre groove depth in the UAE and Oman is 1.6mm. When you wear your tyres down to 1.6mm groove depth then they must be replaced.
This is the highest pressure a tyre can be inflated to. It is measured in kilopascals (kPA).
Which Tyres Will Fit My Vehicle?
You are not restricted to a single size of tyre.
Many different tyres will fit on your vehicle and checking tyre size is much easier than you may realise.
Knowing your existing tyre size is the easy first step in buying a new tyre.
Knowing your existing tyre size is the easy first step in buying a new tyre.
Because many tyres can be fitted on your vehicle, you are not always limited to buying new tyres the same size as your existing tyres.
Your vehicle manual includes important information about the minimum requirements for any tyre that is fitted. Some of this information can also be found on a manufacturer’s sticker sticker placed on the driver side door – it may also be in the glovebox. Look for:
SS (Speed Index) – The minimum speed index rating that can be fitted.
LI (Load Index) – The minimum load index rating that can be fitted.
Size – Most manuals include a recommend size. Check with your tyre dealer because this recommended size is not the only size that will fit.
You should never buy tyres that don’t meet the minimum recommended requirements. You can sometimes buy tyres that exceed the maximum recommended ratings, but you may be paying more for features that are not necessary.
Yes. If you are buying a new set of four tyres it is possible to buy tyres with a different size to your existing tyres. Not all tyres will be suitable but many people are surprised at the number of different tyres that are suitable.
No. If you are replacing one tyre it must be the same size as your existing tyres. It’s widely recommended to replace at least two tyres at once, so the tyres behave the same on one of your vehicle’s axes.