Tyre Maintenance

How to Read the Markings on Your Tyre Sidewall

Glasgow Mobile Tyre Guys
20 December 20255 min read

The numbers and letters on your tyre sidewall tell you everything about size, speed rating, and load capacity. Here is how to decode them.

Every tyre carries a series of numbers and letters moulded into its sidewall that describe its dimensions, construction, and performance ratings. Understanding these markings helps you identify the correct replacement tyre and ensures your vehicle remains safe, legal, and performing as the manufacturer intended.

A typical marking reads: 205/55 R16 91V. The first number — 205 — is the tyre width in millimetres. The second number — 55 — is the aspect ratio, indicating that the sidewall height is 55% of the tyre's width. The letter R denotes radial construction, and 16 refers to the wheel diameter in inches.

The final two elements are the load index and speed rating. In the example above, 91 is the load index, indicating each tyre can support a maximum of 615kg. V is the speed rating, corresponding to a maximum speed of 240km/h. Both figures must meet or exceed your vehicle manufacturer's requirements.

When ordering replacement tyres, always match the full specification shown on your existing tyres unless advised otherwise by a professional. Glasgow Mobile Tyre Guys can identify the correct tyre for your vehicle from your registration number alone, removing any uncertainty from the process.

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tyre sidewall markingstyre size explainedtyre advice Glasgow

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