In the process of buying a car, we usually only care about some of the more practical configurations of the car, but car owners will consider whether the car they buy uses ordinary bias tires or radial tires? If you did not consider this in the process of buying a car, starting today, you have to re-summarize this content into the scope of your own car purchase.
The tire is mainly composed of a tread, a ply, a buffer layer and a bead. Tires can be divided into the following two types according to their structure (that is, the direction in which the cords are arranged in the carcass) (as shown in the figure below): ordinary bias tires and radial tires.
1. Ordinary bias tires
Ordinary bias tire is the structure of ordinary bias tire with inner tube. Bias tire mainly consists of tread, ply, buffer layer and bead. The cords of the ply and the buffer layer of the ordinary bias tire intersect each other and are arranged at an angle of less than 90 degrees to the center line of the tread.
1) Tread: The tread is the outer surface layer of the tire, including the crown, shoulders and sidewalls.
Tire crown: The tire crown is made of wear-resistant rubber, which directly bears friction and all loads, which can reduce the impact of the ply. And protect the ply and inner tube to avoid mechanical damage. There are various uneven patterns on the tread to ensure the adhesion of the tire to the ground and prevent the tire from slipping. The pattern of the tire tread has a very important influence on the performance of the car, so it is necessary to pay enough attention to the pattern of the tire when selecting the tire.
Shoulder: The shoulder is the transition between the thicker crown and the thinner sidewall. In addition to playing the role of protecting the ply, the surface is generally made with various patterns to facilitate anti-skid and heat dissipation.
Sidewall: The sidewall is a thin rubber layer attached to the sidewall of the ply. It can withstand greater distortion and its role is to protect the ply from mechanical damage and moisture erosion.
2) Ply ply The ply is the skeleton of the carcass, also called the carcass.
Its main function is to bear the load, maintain the shape and size of the tire, and make the tire have a certain strength. The ply is usually made of multiple layers of glued cords glued with rubber. In order to distribute the load evenly, the number of plies is usually an even number. The more plies, the greater its strength, but correspondingly its elasticity decreases. Generally, the number of plies is marked on the surface of the tire.
Cord materials generally include cotton thread, rayon thread, nylon thread and steel wire. Now that polyamide fibers and steel wires are used as cords, the number of plies can be reduced under the same load-bearing capacity of the tires, which not only reduces the consumption of rubber, improves the quality of the tires, but also reduces the rolling resistance and lengthens the tires. The service life of the tire.
3) Buffer layer The buffer layer is located between the tread and the ply. It is generally made of two or more layers of sparse cords and rubber with greater elasticity, so it has greater elasticity and can ease the car's use on uneven roads. It can also prevent the tire from separating from the ply when the car is braking in an emergency.
4) Bead Bead is composed of wire bead, ply edging and chafer cloth. It has great rigidity and strength, which can make the tire be firmly installed on the rim.
2. Radial tires
The ply of the radial tire is arranged at an angle of 90o or close to the center line of the tread, which is consistent with the meridian section of the ply tire, much like the radial on the earth, so it is called a radial tire. Figure SS040011 shows the structure of radial tires. Due to the arrangement of the plies, the number of plies of radial tires can be reduced by about 40%-50% compared with ordinary bias tires. The radial tire is only connected by rubber in the circumferential direction, so in order to withstand the large tangential force generated during driving and improve the rigidity of the tire, the radial tire also has several layers of cords at a large angle with the meridian section (the included angle is 70- 75), a belt layer similar to a buffer belt with higher strength and not easy to stretch in the circumferential direction. The belt layer is generally made of fabric cord (such as glass fiber, polyamide fiber) or steel cord with high strength and low tensile deformation.
Advantage
Compared with ordinary bias tires, radial tires have the following advantages:
Low rolling resistance and fuel saving: Due to the belt layer, the tangential deformation and relative slip of the crown after the tire hits the ground is much smaller than that of ordinary tires, and the sidewall of radial tires is thin and the radial deformation recovers quickly. These two features are beneficial to reduce the internal wear of the tire and reduce the rolling resistance. Tests prove that the rolling resistance of radial tires is 20% to 30% lower than that of ordinary bias tires, which can save fuel by 5% to 10%.
The tread has good abrasion resistance and long service life: when the wheel rolls, the surface of the tire on the ground is deformed and slipped. The deformation promotes slippage, which intensifies the wear of the tread. Due to the rigidity of the crown of the radial tire, the deformation is small, and there is almost no slippage. In addition, the crown contact area is large, the unit pressure is small and uniform, so the tread wear is reduced. Tests have proved that the service life of radial tires is 30%-40% longer than that of bias tires.
Large elasticity and good cushioning: Because the radial tire cords are arranged in a radial direction, when the wheel rotates, the deformation of the tire perpendicular to the ground is greater than that of a bias tire. The carcass is soft and elastic, which improves the smoothness of the car.
Strong puncture resistance: Because the radial tire has a hard belt layer, it greatly enhances the puncture resistance of the tire crown, reduces the risk of tire blowout, and improves driving safety.
Large adhesion: Radial tires have a larger ground contact area when driving, and at the same time, due to the action of the belt layer, the ground pressure distribution is more uniform, thereby improving the adhesion and reducing the side slip phenomenon.