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How to read car tyre sizes ?

Whenever you are buying a new or replacement tyre, it’s essential that you get the right one. The size and type of tyre will differ between a vehicle’s make and model.  For most tyres, you will be able to find the information about the size of your tyres required on the tyre’s sidewall.

You will see a bunch of different numbers which may not make sense to you. How can you read car tyre sizes? Do these numbers mean anything?

An example of a car tyre size may read “205/55 R16 91V” This may not make much sense upon first glance, but when you realize that each number or letter denotes a specific piece of information about the tyre, it’ll all start to make sense.

Here’s how to read car tyres. Let’s start by breaking down the numbers, for example – 205/55 R16 91V.


The first digits that appear at the start of the car tyre size are the width in millimetres.

Your car will need a tyre of a specific width (though there are tolerances). But tyre width is fairly standardised across the board.

You may find that some vehicles will have different widths of tyres between the front and the back. Having a staggered set of tyres with wider rear tyres helps the car grip the road better when there is a rear or mid-engined configuration.



The second number in the set is the profile or aspect ratio. The profile is the height of the sidewall of the tyre.  The measurement is actually expressed as a percentage of the tyre’s width. In our example, the tyre wall is equal to 55% of the width of the tyre.

Where a tyre has a low aspect ratio, it will often perform to a higher standard than a tyre that has a higher aspect ratio, due to the lower flex and stiffer sidewall construction.



Next up we come to the radial construction. This number represents the diameter of the inner rim of the tyre. This is measured in inches. The larger the rim, the bigger the tyres. Quite often, these bigger tyres will end up costing you more money.



This final number refers to the tyres load rating. This lets you know how much weight a tyre will be able to carry.

Of course, the number that you see on the tyre is not the weight. If you check out what is known as a load index you’ll be able to translate this figure into a meaningful piece of information.

In the case of our number, 91, the load that can be carried in Kg is 615kg. This is limited to the amount of weight that a single tyre will be able to hold.

You may overlook this number, however, in the event of an accident in your car, if your carload rating is lower than the combined load weight, then you’ll run into trouble if you’re trying to claim off your insurance or make use of the warranty.



The letter that follows the last number relates to the maximum speed that a vehicle will be able to travel. In the case of our letter, “V”, this refers to a maximum speed of 149mph.

The letter is important to pay attention to. If you start to drive at speeds above 149mph, then you may find that your tyres heat up considerably. Do much more than this and you may end up setting fire to your car.


Additional Information

You may find that your tyre has extra letters on the end. These will give information about the tyre and how it should be used.

In the case of the letters XL, these refer to an extra load. A vehicle with a tyre that is rated XL will be reinforced and able to carry much heavier loads.



The flanged rim is an area of your tyre that has additional rim protection.

This extra protection is there to stop kerb damage and usually consists of a rubbed bead running along the outside edge.

This rating may only be available on specific brands of tyre.

Searching for the Right Tyre for You

If you are needing a new tyre for your car, make sure and pay attention to all of the sizing information on the side of the tyre.

Aside from the practicalities associated with knowing which size tyre you need to order, there are some other major pieces of information that you need to understand such as the amount of weight that a tyre can hold and the top speed that you can travel with it on.

If you’re shopping for a particular size of the tyre, you’ll most likely need to type in the size of the tyre into Google, for example, 235/55 R17 Tyres tyres or 245/45 R18 Tyres.

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