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What do the different numbers and letters represent on the side of a tyre?


Have you ever glanced at the side of a tyre and been bewildered by the array of numbers and letters? Fear not, for you're not alone. Tyre sidewall markings might seem like a cryptic code at first, but once decoded, they reveal crucial information about your tyres. In this blog post, we'll unravel the mystery behind those alphanumeric characters, empowering you to make informed decisions about your vehicle's footwear.

Understanding Tyre Sidewall Markings: When you take a closer look at the sidewall of a tyre, you'll notice a sequence of letters, numbers, and symbols. Each element serves a specific purpose, providing valuable insights into the tyre's size, performance capabilities, and manufacturing details.

writing on the side of a tyre
Finally, you can understand it all!

Let's break down the most common components, Tyre letters and numbers:

  1. Tyre Size: The first set of characters typically indicates the tyre's size. This includes parameters such as width, aspect ratio, and rim diameter. For example, in a marking like "205/55 R16," 205 represents the tyre's width in millimetres, 55 denotes the aspect ratio (the height of the sidewall as a percentage of the width), and 16 indicates the rim diameter in inches.

  2. Load Index: Following the tyre size, you might find a two or three-digit number representing the load index. This figure indicates the maximum weight that the tyre can support when properly inflated. The higher the number, the greater the load-bearing capacity.

  3. Speed Rating: Adjacent to the load index, you'll typically encounter a letter indicating the tyre's speed rating. This letter corresponds to the maximum speed at which the tyre can safely operate under optimal conditions. Common speed ratings include "H" for up to 130 mph, "V" for up to 149 mph, and "W" for up to 168 mph.

  4. Construction Type: Some tyres feature additional markings to denote their construction type. For instance, "R" signifies radial construction, which is the most common type in modern tyres. Other construction types include "D" for diagonal (bias-ply) and "B" for belted bias.

  5. DOT Code: Towards the end of the sidewall, you'll often find a DOT (Department of Transportation) code. This alphanumeric sequence includes details about the tyre's manufacturing plant, production date, and other specifications. By decoding the DOT code, you can determine when the tyre was manufactured and assess its age.


While tyre sidewall markings may seem perplexing at first glance, they serve as invaluable guides for selecting the right tyres for your vehicle. By understanding the significance of each number and letter, you can make informed choices that enhance safety, performance, and longevity. So, the next time you inspect your tyres, take a moment to decipher the alphabet soup on the sidewall—it's the key to unlocking a world of valuable information.

For an excellent Tyre fitting and Wheel Balancing service in Essex & Harlow, Visit

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