The Importance of Tyre Markings and How to Read Them

An understanding of the correct tyres for your vehicle is crucial, so it is important you get it right. They are one of the key influencers for the handling and safety of your vehicle. If the wrong tyres are fitted to your vehicle this can cause an incorrect reading to your speedometer thereby jeopardising yours and your passengers’ safety. With the tyre markings provided (See below under “where to find tyre markings”) you will be able to determine a suitable tyre for your vehicle. Whilst this can be daunting at first and tempting to overlook, the following explanation  will help you form a clear understanding of the requirements.

Where can I find tyre markings?

You would think that this is self-explanatory right? Although this is correct and the markings can be found engraved into the sidewall of your tyre. It is important to note that the markings only represent the specifications of that tyre and not whether it is suitable for your vehicle.

To be certain a tyre is correct for your vehicle and what your manufacturer recommends you should refer to your vehicle owner’s manual or any other alternatives listed below:

  • The vehicles owner’s manual (this is an instructional book specifically for your vehicle)
  • Inside the fuel cap
  • Inside the glove box
  • The driver’s side door jamb (the door jamb is the space on the vehicle where the door connects to the body of the car)

Understanding your tyre’s sidewall markings in 6 simple steps!

With the combination of letters and digits situated on the tyre, it is easy to get overwhelmed. So we have broken it down into 6 simple steps establishing the purpose of each marking individually.

We will use the following markings as an example: 205/65 R15 94H

  1. Tyre Width

205/65 R15 94H

The first number we will look at is ‘205’ This indicates the width of the tyre in millimetres. This portion of the tyre is measured from sidewall to sidewall.

  1. Profile

205/65 R15 94 H

The two-digit number after the slash indicates the profile of the tyre, this can also be referred to as the ‘aspect ratio’. This is the height of the sidewall. The example above ‘65’ represents the ratio of the tyre’s cross-section to its width, this is measured as percentage of the tyre’s width e.g. 65% of ‘205

  1. Tyre Construction

205/65 R15 94 H

We come across our first letter ‘R’ which represents that the tyre has a radial construction.

  1. Rim Diameter

205/65 R15 94H

The following number in this sequence represents the diameter of the wheel rim, measured in inches. In this example ‘15’ would mean you need a tyre that matches a wheel of 15 inches.

  1. Load Index

205/65 R15 94H

The following two-digit number represents the load rating, which is the maximum capacity of a passenger car tyre – at the maximum safe pressure. A load index table is available to help you to determine the maximum load weight.

  1. Speed Rating Index

205/65 R15 94H

The final letter in this section represents the speed rating. This stands for the maximum speed a tyre can handle when it is correctly inflated and under load. In the example above the ‘H’ means the tyres are safe for use up to a maximum speed of 130mph. To understand what each letter represents, a table is available –

So if you’re shopping for a particular size of 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.

Daniel Maynard

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