What is the tire load index?

Introduction

The tire load index is one of the most important technical parameters to understand before purchasing tires for your vehicle. It indicates the maximum load a tire can support at a given pressure. For every driver, especially those using vans or trucks, knowledge of this parameter is crucial to ensuring vehicle safety and efficiency.

History of the load index

The concept of load index emerged with the development of the automotive industry in the 20th century. As the number and diversity of vehicles increased, tire manufacturers began developing technical standards that allowed for the precise definition of their product parameters. In the 1950s, international organizations such as ETRTO (European Tyre and Rim Technical Organization) introduced unified load indexes, allowing for better adaptation of tires to different types of vehicles and road conditions.

The importance of the load capacity index in practice

The load index is crucial for road safety. Exceeding the maximum load can lead to tire damage or even explosion while driving. Therefore, it's crucial to choose tires according to the vehicle manufacturer's recommendations.

This index is particularly important for delivery vehicles, trucks, and buses, where axle loads are significantly higher than in passenger cars. Additionally, the load index is important for sports vehicles, where tires must withstand the high forces exerted during high-speed driving.

Load index table

Load index	Maximum load (kg)
50	190
60	250
70	335
80	450
90	600
100	800
110	1060
120	1400

The table shows sample load indexes and their corresponding maximum loads. It's important to remember that these numbers apply to a single tire, so they should be doubled for each axle.

How to read the load index on a tire?

The load index is typically listed on the sidewall of the tire, along with other parameters such as width, profile, and diameter. For example, 205/55 R16 91V means:

• 205: tire width in millimeters,

• 55: tire profile (height to width ratio),

• R16: rim diameter in inches,

• 91: load index,

• V: speed index.

For a 91-rated tire, the maximum load is 615 kg. It's important to choose tires with a load index that matches the vehicle's requirements.

The impact of the load index on safety

The appropriate selection of the load index has a direct impact on driving safety.Too low an index can lead to:

• Excessive tire wear,

• Increased risk of puncture or explosion,

• Reduced vehicle stability at high speeds.

In turn, choosing tires with a higher index than required may affect driving comfort and fuel consumption, as such tires are usually stiffer and heavier.

Summary

The load index is a key parameter that should be considered when selecting tires. It ensures not only safety but also optimal vehicle performance. The history of this index demonstrates the importance of standardizing automotive standards to ensure compliance and reliability. Thanks to the tables and markings on the tires, every driver can easily check whether the selected tires meet their vehicle's requirements.