① Under certain load and driving conditions, the tire of the forklift has a suitable tire pressure. When the tire pressure is lower than the standard value, the radial deformation of the tire increases and excessive deflection occurs on both sides, so that both sides of the crown are grounded, the inner wall of the sidewall is compressed, the outer wall of the sidewall is pulled, and the cord in the tire body produces large deformation and alternating stress. The periodic compression deformation will cause the fatigue damage of the return cord, increase the relative slip between the tire ply and the tire and the ground, increase the heat generated by friction, and sharply increase the tire temperature, reduce the tensile strength of the rubber, loosen and partially delaminate the cord, and burst the tire when it is impacted by obstacles. The uneven pressure on the tread causes serious wear on the shoulder, resulting in "bridge effect", and the tread is toothed or wavy. The concave part of tire pattern is easy to be embedded into nails and stones on the road, causing mechanical damage. The rolling resistance of the carcass increases and the fuel consumption increases. The test shows that when the tire pressure is lower than 20% - 25% of the standard value, the fuel consumption increases by 20%. When the tire pressure is higher than the standard value, the center of the tire crown is grounded, the contact area between the tire and the road surface is reduced, the load per unit area is increased, and the wear in the middle of the tire crown is intensified. The tire cord is over stretched, the tire cord stress increases, and the tire cord fatigue process speeds up, resulting in cord breakage and early tire burst.
② Under a certain load and tire pressure, with the increase of vehicle speed, the deformation frequency of tire, the vibration of tire body and the distortion and deformation of tire circumference and side (forming static wave) will increase, the heat generated by friction per unit time will increase, the working performance of tire will decline, and even ply rupture and tread spalling will occur, accelerating the wear and damage of tire.
③ Under a certain tire pressure, the tire overload will increase its deflection and deformation, and the stress of cord fabric and cord will increase, which is easy to cause cord breakage, looseness and cord fabric delamination at the tire wall. The stress of carcass cord will exceed the design allowable stress and tire grounding pressure, resulting in increased heat, increased tire temperature and decreased bearing capacity. At the same time, wear occurs due to the contact between the tire shoulder and the ground. Especially when encountering obstacles, even a small stone will cause the tire crown to explode. Practice has proved that when the tire load exceeds 20%, the driving mileage will be reduced by 35% when driving on turns and uneven roads; When it exceeds 50%, it will be shortened by 59%; When it exceeds 1 time, it will be shortened by more than 80%.
④ Road conditions also have a great impact on the service life of tires, which affects the friction between tires and the ground and the dynamic load on tires.
⑤ High temperature will reduce the breaking strength, elongation and hardness of rubber, reduce the adhesion strength between rubber and cord, and accelerate the aging of rubber. For tires under high temperature, especially aged tires, when they slip or roll over obstacles, it is easy to tear the crown pattern. Cracks due to the aging of tire wall rubber and serious deformation of tire wall lead to the separation of tire cord and rubber. Once the tire encounters sudden load, it is likely to burst.
⑥ When the tire is corroded by grease, acid-base substances and high temperature for a long time, the physical and chemical properties of the tire will change, the bearing capacity will be greatly reduced, and the tire is also very easy to burst in use. In addition, the tires corroded by oil will have massive peeling off of the sealing layer, small area rubber peeling off of the tire mouth, and separation of the carcass cord from the rubber. Because the patch cannot be compatible with the oil-bearing rubber, even if the damage wound of the tire is very small, the possibility of repair is lost.
⑦ Due to the different loads distributed by the front and rear axles, the different working characteristics of the driving wheels and steering wheels and the differences in road conditions, the wear conditions of each tire are inconsistent. If the tires of the same factory, the same size, structure, level and pattern are not replaced on both sides of the same axle, the tire wear will be accelerated.
⑧ If the tire is not matched properly, it will also cause uneven tire wear during regular use.
