The tyre speed index, also known as the speed rating, is a code that indicates the maximum speed at which a tyre can safely operate.
For the average individual, the meaning of speed symbols and load indexes on automotive tyres are not common knowledge. This makes sense, as most passenger cars with the correctly chosen tyres won’t ever come close to the maximum speed or weight capacity indicated on the tyres.
It is represented by a letter found on the sidewall of the tyre, following the tyre size and load index. The speed index is an important consideration as it ensures that the tyre is suitable for the speed capabilities of the vehicle.
Each letter in the speed index corresponds to a specific maximum speed rating. For example:
- "Q" indicates a maximum speed rating of up to 160 km/h
- "H" indicates a maximum speed rating of up to 210 km/h
- "V" indicates a maximum speed rating of up to 240 km/h
- "Y" indicates a maximum speed rating of up to 300 km/h
- "W" indicates a maximum speed rating of up to 270 km/h
When replacing tyres, it is advisable to choose ones with a speed index at least equal to or higher than the original equipment manufacturer (OEM) specifications. However, it is generally not recommended to fit tyres with a higher speed index than necessary, as it may affect the ride comfort and cost more without providing any significant benefits.
It is worth noting that the load capacity index is based on single tyre application. If your vehicle has dual tyres on the same axle, you'll need to consider the load rating per tyre and make sure the combined load capacity of both tyres is sufficient for the intended weight.