When buying tyres, it is not enough to check only the size. It is just as important to understand the load and speed index, as they determine whether the tyre is suitable for the vehicle’s weight and intended use.
What is the load index
The load index indicates the maximum weight that one tyre can carry at the correct pressure. This is especially important if the vehicle is often used with heavier loads, luggage, or multiple passengers.
Where to find it on the tyre
The load and speed index are usually shown immediately after the tyre size. For example, in the marking 205/55 R16 91V, the number 91 is the load index, and the letter V is the speed index.
What the load index means in practice
The higher the number, the more weight the tyre can carry. For the buyer, this means the tyre must be suitable not only for the vehicle itself but also for how it is used. If the vehicle is often fully loaded, a load index that is too low is especially undesirable.
What is the speed index
The speed index is a letter that indicates the maximum speed for which the tyre is certified. Even if you do not drive at maximum speed on a daily basis, this rating must still match the vehicle’s requirements and the tyre’s construction.
What the speed index means in practice
The letter in the tyre marking is not decorative. It indicates the level of performance the tyre is designed for. Choosing a tyre with an unsuitable speed index may mean it is not appropriate for the specific vehicle or its usage conditions.
Why it matters
If the load or speed index is too low, the tyre may not be suitable for the vehicle and its operation. This can affect safety, wear, and tyre performance under higher loads.
Can you choose a higher index
In many cases, a higher load or speed index is acceptable, but you should not choose one lower than the manufacturer’s specified minimum. If in doubt, it is safer to compare with the vehicle manufacturer’s recommendations.
How to check the correct index
The safest way is to compare the selected tyre with the information shown on the current tyre or in the manufacturer’s recommendations. If the new tyre has a lower load or speed index than required, it is not the right choice.
Common mistake when buying tyres
One of the most common mistakes is focusing only on the size while ignoring the numbers and letters that follow. However, this part of the marking determines whether the tyre is suitable for the specific vehicle and load.
What to check before buying
- the full tyre marking, not just the size
- whether the load index is not lower than required
- whether the speed index matches the vehicle’s requirements
- whether the index matches the current tyres or manufacturer recommendations
- whether the vehicle is often driven at full load
- whether the tyres are intended for city, highway, or more intensive use