The tyre size is not just a sequence of numbers on the sidewall. It affects the vehicle’s handling, comfort, fuel consumption, and even the operation of electronic systems. That is why, before purchasing, you should always make sure the selected size matches the manufacturer’s requirements.
Where to find the correct size
The manufacturer’s recommended tyre size is usually indicated inside the driver’s door frame, on the fuel filler cap, or in the vehicle’s owner’s manual. This is the safest place to start your search.
How to read the size marking
For example, the marking 205/55 R16 indicates the tyre width in millimetres, the profile ratio in percent, and the rim diameter in inches. In addition, the load and speed index are often shown as well.
Consider your existing rims if you are not planning to change them
If you do not plan to replace your rims, the tyre diameter marking, such as R16, R17, or R18, is especially important. This means the new tyre must match the diameter of your current rims. If your car has 16-inch rims, the tyre must also be designed for 16-inch rims. An incorrectly chosen diameter simply will not fit the existing rim.
If you are not changing rims, check the full setup
You should not look only at tyre width and profile, but also ensure that the selected size matches the rims already fitted to your car. Even if other parameters seem similar, an incorrect diameter means the tyre cannot be mounted on the existing rim.
Why you should not guess the size
An incorrect tyre size can affect steering precision, braking distance, wheel arch clearance, and the proper functioning of electronic assistance systems. Even small deviations are not always a safe choice.
What to do if multiple sizes are allowed
Some vehicles allow more than one tyre size. In this case, the choice may depend on driving style, rim diameter, availability, and budget, but it should always stay within the manufacturer’s specified limits.
What to check before ordering
- tyre width, profile, and diameter
- whether the diameter matches your existing rims if you are not replacing them
- load and speed index
- season and intended use
- whether the choice matches the vehicle manufacturer’s recommendations