Knowing your tyre size helps you replace your tyres correctly, maintain safe handling, and avoid fitting issues. The good news is that the information is already printed on your current tyres.
Where to find your tyre size
Your tyre size is printed on the outer sidewall of the tyre as a sequence of numbers and letters.
You will usually find it clearly visible when looking at the side of the tyre, although you may need to turn the steering slightly to see the front tyres.
What the numbers mean
A typical tyre size might look like 225/40 R18 92Y. Each part of this code gives specific information about the tyre.
The first number (225) is the width of the tyre in millimetres.
The second number (40) is the aspect ratio, which represents the height of the sidewall as a percentage of the width.
The letter R indicates radial construction, and the number after it (18) is the wheel diameter in inches.
The final numbers and letters refer to the load index and speed rating of the tyre.
Why the correct tyre size matters
Using the correct tyre size ensures your vehicle handles properly and maintains accurate speed readings.
Incorrect tyre sizes can affect braking performance, fuel efficiency, and overall safety.
If you are unsure, always check your vehicle handbook or speak to a professional before fitting new tyres.