Load Index and Maximum Load Relationship

“load index,tire pressure,tire structure type, tire pattern,  tire vertical load, vehicle speed, and tire working condition.”

Factors related to vehicle tires mainly include:

tire structure type, tire pattern, tire pressure, tire vertical load, vehicle speed, and tire working condition.

Tires are mainly divided into two types according to their structural characteristics: bias tires and radial tires. Bias tire adopts composite angle fabric ply structure, and uses composite angle fabric tire protector at the crown; radial tire adopts single radial steel belt ply structure, and uses composite steel belt tire protector at the crown . 

The above-mentioned structural characteristics make the carcass of the bias tire easy to deform, the tire has a large envelope characteristic, and the ride comfort is good. A part of the curved tire carcass becomes flat when it comes into contact with the flat road surface, and the tire expands to make the road surface horizontal. friction. As for radial tires, the carcass is not easy to expand and contract, has small envelope, and has the characteristics of strong acceleration, braking and maneuverability.

The tire is in direct contact with the road surface through the pattern of its tread. The main function of the pattern is to ensure that there is a sufficient friction coefficient between the tire and the road surface. Different pattern shapes will inevitably bring about different properties of the contact interface, which will affect the magnitude and distribution of the contact stress on the interface. 

In practice, it is often selected according to road conditions and vehicle use requirements. Commonly used tread patterns mainly include longitudinal groove pattern, transverse groove pattern, mixed pattern, block pattern and asymmetric pattern. Longitudinal pattern tire is the most commonly used type of tire tread pattern in research problems.

The size of the tire pressure directly affects the size of the tire vertical stiffness. As the inflation pressure increases, the vertical stiffness of the tire increases, the tire deformation decreases, the contact area between the tire and the road surface decreases, and the average ground contact stress increases. 

As far as the impact on the ground stress distribution is concerned, it is generally believed that the ground stress concentration in the middle changes with the tire pressure, while the ground stress at the edge of the track is less affected by the tire pressure. Tire pressure is one of the key factors affecting the size and distribution of tire-road contact stress.

The vertical load borne by the tire directly affects the magnitude and distribution of the vertical contact stress. When the inflation pressure is constant, the tire footprint increases with the increase of the vertical load; when the vertical load increases to a certain value, the tire footprint width reaches the width of the driving surface; the vertical load continues to increase, the tire footprint width remains unchanged, and the footprint length increases. 

The area increases; the increase of load and ground area also causes complex changes in the distribution of ground pressure. Changes in the size and distribution of vertical ground stress will inevitably cause changes in the response of horizontal friction on the contact interface. Tire vertical load is one of the key factors affecting the magnitude and distribution of tire-road contact stress.

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