When you look at a tyre sidewall, you will see something like 205/55 R16 91V. To most drivers this looks like a random code, but each part tells you something specific about the tyre. Understanding it helps you buy the right replacement and communicate accurately with any tyre fitter.
Breaking Down the Numbers
The first number — 205 in our example — is the tyre width in millimetres, measured from sidewall to sidewall. The second number — 55 — is the aspect ratio, meaning the sidewall height is 55% of the tyre's width. The letter R indicates radial construction, which is standard on all modern passenger tyres. The final number — 16 — is the wheel diameter in inches that the tyre fits.
What Are the Speed and Load Ratings?
The numbers and letters after the wheel size refer to load index and speed rating. The load index (91 in our example) indicates the maximum weight each tyre can safely support. The speed rating (V) indicates the maximum sustained speed the tyre is designed for. Fitting a tyre with a lower speed rating than your vehicle requires is both unsafe and illegal.
Where to Find Your Correct Tyre Size
Your vehicle's required tyre size is printed on the sidewall of your existing tyres, inside the driver's door jamb on a sticker, and in your owner's manual. If you are unsure which size you need, call us on 0141 673 6841 and our team will identify the correct tyre for your vehicle from your registration plate alone.