The impact of tire structure on tire performance is complex and not direct. From the user’s point of view, the performance of tires can be summed up in two points: the first is that the carcass must be firm and durable, that is, there will be no problems such as bursting and air leakage during the driving of the car; the second is that the tread must be grounded. Flat, that is, stable driving, reliable braking performance, and good tread wear resistance. To put it simpler, it is nothing more than the carcass problem and the tread problem, and these two problems can still be combined into one, because the structure of the carcass controls the performance of the tread when the car is running. Play.
Below, I will discuss with the editor how the tire structure determines tire performance. This should also be analyzed from two major aspects:
1. The carcass structure determines the shape of the tread and thus determines the performance of the tire directly related to the shape of the tread.
The shape of the tire tread and its changes when the tire is running are important factors that affect the performance of the tire. Radial tires benefit from the tightening effect of the belt layer. Under normal inflation pressure, the crown and shoulders are basically kept in line. However, due to the higher inflation pressure, the crown of the truck tire is slightly raised, but the curvature is not biased. So big.
The properties affected by the shape of the tread are:
1. Stability of driving
As the tread changes from an arc to a straight line, the effective width of the tread will increase until the shoulders and the crown touch the ground at the same time, which will significantly improve the lateral support of the car and thus become more stable.
2. The braking distance is shortened
The flat tread helps maintain adhesion to the ground, thereby shortening the braking distance.
3. Rolling resistance
When the car is at a standstill, there is a contact surface between the tread and the ground, commonly known as an imprint. Because of the curved tread of the bias tire, its impression is elliptical, the front and rear spacing is larger, and the side spacing is narrow, while the radial tire imprint is closer to a rectangle, with a short front and rear spacing and large side spacing. Under the same pressure, the print area of the two is almost the same. This is the fundamental reason why radial tires have lower rolling resistance.
4. Anti-skid
Whether driving in a straight line or turning, a flat tread can always make the tire tread more effectively contact the ground, enhance the tire’s grip, and reduce the possibility of sideslip.
5. Wear resistance
Why does a flat tread have better wear resistance? The most basic reason is also the tread shape. because:
First, during the driving process, the tread shape of the radial tire remains basically unchanged, so the useless work is small, the heat generation is small, and the fatigue and aging of the material are slower than that of the bias tire.
Second, the flatter the tread, the more uniform the force is, especially the pressure of the crown is significantly reduced, and the reduction of the force is a necessary condition for improving the wear resistance of the tread. An important factor in tread wear is the scraping force of the ground. The greater the scraping force, the faster the tread wears. For a tread with a high crown, the crown part bears the greatest pressure, until the shoulders gradually weaken, so the scraping force experienced by the shoulders is also the largest. This causes the tire to always wear from the crown and then expand to the entire tread. Some radial tires will wear the crown because the crown is too high.
Third, eccentric wear is not easy to occur.
Second, the tire structure also directly determines the performance of the carcass itself. Mainly manifested in:
1. The circumferential consistency of the center line of the tire crown.
The belt layer of radial tires can ensure that the centerline of the tread is consistent with the centerline of the crown, that is, the centrifugal force balance during high-speed rotation is significantly better than that of bias tires.
2. Sidewall rigidity and maintainability
Viewed from the side, the arrangement of radial tire steel wires is similar to fan bones, and each steel wire is on the radius line. Because radial tires generally have a single-layer carcass structure, the steel wires neither overlap nor cross, and the gap between the steel wires is Sealed by rubber (commonly known as “sidewall rubber”). The sidewall of radial tires is fan-shaped. Once pierced by external force, it is prone to curtain cracks and cannot be repaired.
3. The carcass heats up
There are two main parts of carcass heat generation, one part comes from the carcass frame material and sidewall rubber, and one part comes from the air in the tire. The main reasons for the heat generation of the carcass are: First, the carcass of the tire deforms under load. When a car turns or the road surface has ups and downs, the tire shape is prone to deformation due to the force of the road surface and the car’s own weight. The second is that the dynamic load of the tire is constantly changing when the car is running, so the carcass will expand and contract. The third is the frequent squeezing and flow of air in the tire due to the change of the carcass shape and the expansion and contraction of the frame material. In fact, there are two key elements in the heat generation of tires, namely the internal energy and movement of the material. When the internal energy of a material is excited, it generates heat. Thermal energy is one of the basic properties of matter, and movement is the excitation condition. The design of the tire is to reduce unnecessary movement as much as possible. Only in this way, the heat generated by the same ** material will naturally be reduced.
4. Load performance
The load-carrying performance of a tire is not only determined by the strength and quantity of the frame material, but also by the strength of the traveler. The angle between the carcass wire of a radial tire and the traveler is a right angle. It is generally believed that the arrangement of radial tires can better exert the strength performance of the frame material. This is actually a misunderstanding. The final stressed component of the tire is the wire ring, and both ends of the carcass wire are all fixed on the wire ring. The force form of the tire is not just a simple pulling force, but mainly the external expansion force of the internal pressure of the gas. This tension is perpendicular to the inner wall of the tire. In other words, regardless of the angle between the cord and the traveler, the force of the internal pressure acting on the cord is always vertical. Furthermore, when the two ends are fixed and the distance between the ends is constant, whether it is a fiber or a steel wire, its breaking strength, tensile strength and other physical properties will not be caused by the fixed point or line (such as traveler) and its own The angle changes. That is to say, the structural design of the tire is determined by the strength of the wire bead, the frame material, the size of the tire cavity, and the inflation pressure.
There is also a view that 70% of the load strength of radial tires is concentrated on the belt layer, but this is not the case in reality. The load strength of the belt layer is inversely proportional to the aspect ratio of the tire section. The smaller the aspect ratio, the greater the load strength of the belt layer, and vice versa.
