Load and speed index for truck tyres

Load and speed index of truck tyres

The load index is the official code that indicates how much weight a single tyre can carry at the correct tyre pressure. This value is always shown on the sidewall of the tyre, directly next to the speed index.

Never use a tyre with a lower load index than the vehicle’s original specification. Exceeding the permitted load can lead to excessive deformation, heat build-up and, in extreme cases, tyre failure.

Especially in countries where trucks are structurally overloaded, such as Germany and Poland, the correct load index is crucial for both safety and tyre lifespan. In the load index table below, you can find the exact load capacity corresponding to each index value.

When fitting tyres, always check that tyres on the same axle have identical load indexes. A higher load index on one side can never compensate for a lower index on the other.

Tyre pressure and load capacity

The load capacity of a tyre is only valid at the correct tyre pressure.

Too low pressure leads to increased deformation, heat build-up and higher fuel consumption. Too high pressure reduces the contact patch and decreases grip, especially in wet conditions.

The correct tyre pressure offers four key benefits:

• maximum load capacity
• even wear
• lower fuel consumption
• improved driving safety

By checking tyre pressure regularly, you prevent carcass damage and extend tyre life. Transport operators in the Benelux often operate with variable loads and therefore benefit even more from correct pressure settings.

For international transport in the DACH region, stable tyre pressure is essential to protect the vehicle combination against heat stress at higher speeds.

Load index when replacing truck tyres

When replacing truck tyres, the load index of the new tyre must be at least equal to that of the original tyre. A higher load index is always allowed; a lower one is not.

This is because the load index applies to each individual tyre. Two tyres on the same axle must always have the same load index to prevent imbalance and uneven load distribution.

A tyre with a significantly higher load index on one side does not compensate for a lower index on the other. This can lead to cracking, instability and tread deformation.

In practice — such as distribution vehicles in the Netherlands or heavily loaded tractor units in Eastern Europe — incorrect load index selection is one of the most common causes of premature tyre damage.

What is the speed index of a truck tyre?

The speed index is the code that indicates the maximum speed a tyre can safely handle. This speed is determined by the manufacturer through laboratory testing, where the tyre runs against a metal drum at increasing speeds.

The speed index is shown next to the load index on the tyre sidewall. Each letter or letter/number combination corresponds to a specific speed range, such as A8 (40 km/h), F (80 km/h), or T (190 km/h).

Even tyres that are rarely used on public roads are assigned an official speed index.

The specified maximum speed only applies to tyres that are not damaged, not overloaded and not underinflated. Repaired tyres generally no longer retain their original speed index, as the quality of the repair affects heat management.

Safety and speed index in practice

Respecting the speed index is essential to prevent overheating, cracking and possible carcass failure.

Trucks operating at higher average speeds, such as international transport vehicles, are particularly sensitive to heat build-up when the speed index is insufficient.

Tyre pressure also plays a major role: a tyre with too low pressure deforms more and heats up faster, effectively reducing its maximum safe speed.

In regions such as Germany, where sections of motorway have no speed limit, many transport operators deliberately choose higher speed index ratings. However, the intended use remains key:

A city distribution vehicle, for example, does not require a high speed index, but does require a higher load index. The combination must always match usage, speed and load.

Load index and speed index tables

In the table below, you will find the full list of official load index values, including the corresponding maximum load capacity. Below that, you will find the complete speed index table with all speed classes from A1 to ZR.

These tables are based on international standards and apply to all truck and trailer tyres used in Europe.

Use these tables when selecting new tyres, converting vehicles or making technical comparisons between different brands. The combination of load and speed index determines which tyre is suitable for a specific vehicle type and application.

If in doubt, always consult the vehicle documentation or ask our experts for advice.

Load index tyres

Speed index (SI)

Frequently asked questions (FAQ)

1. What does the load index on a truck tyre mean?

The load index indicates how much weight a single tyre can safely carry at the correct pressure.

2. Where can I find the speed index?

The speed index is always shown next to the load index on the tyre sidewall.

3. Can I use tyres with different load indexes on the same axle?

No, both tyres on the same axle must always have the same load index.

4. Does the speed index apply to repaired tyres?

No, repaired tyres no longer guarantee the original speed index.

5. What happens if tyre pressure is too low?

Too low pressure increases heat build-up, wear and the risk of tyre failure.

Want to know more?

Want to be sure that the load index and speed index of your future tyres match your vehicle and application? Our specialists are happy to advise you on the correct tyre pressure, tyre selection and positioning on the vehicle or trailer.

In our webshop, you will find both the load index and speed index for each tyre.

For more information, please contact our experts on +31 (0)523 850 850. Become a customer and register directly via this page.