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The choice and use of the tire should be according to the load, speed, road condition and climate environment. Can you choose the correct tire? The tire is one of the most important components of the automobile driving mechanism, which is directly related to the safety and operation economy. If you can't choose and use tire correctly, not only it can reduce the performance indexes but also affects the driving safety, and even cause unnecessary casualties and property losses. Here's some detailed selection methods:
The basic principles of choice
Firstly, determine specifications of the tire according to the load capacity and speed calculated by shaft load, which involves the performance index and driving safety of the vehicle.
Secondly according to the structure characteristics of the vehicle (e.g. tractor, dump truck, mixers, etc.), road conditions, climate and so on, determine the structure of the tire (radial tire or common tire) and tire pattern to meet the vehicle passing through performance, riding comfort and steering characteristics as well as interchangeability and maintenance convenience requirements. and then evaluate economical efficiency.
Finally, consider the other auxiliary requirements of the tire, such as the stability of the tire source and the problems of vehicle management.
The basic principle and detailed method of choice
When choosing a tire, you must first make sure that the tire is not overloaded. If tire overload, it not only can produce abnormal tire wear causing sharply shorten life, but also sometimes causing not enough stiffness and bad adhesion performance, which seriously influence the stability of vehicle, and even sudden flat tire may happen. For the same specification, the tire may have different load capacity, and the following items should be paid attention to.
The same specification of tires have different structural plies, so the load capacity is different, choose carefully.
The same specification tires is not the same as single or dual mounted. When dual tires mounted, because the road camber and axle bending deformation under load, inside and outside tire load is different, carrying capacity of two tires is about 72 times of single tire, not 2 times.
The principle of the second choice of tire is that the load capacity of the tire is according the higher value, and the front and rear axle must be considered at the same time.
Determine the speed level
The same specifications tires not only have different load capacity, but also have different speed level, sometimes tires are not overload, but are possible over-speed, which will cause excessive hot, excessive wear, and flat tire. tire over-speed could lead to the following phenomena:
Overheating tires can lead to excessive wear and even blasting.
Vehicles in the process of driving, if tire speed exceeds to a certain degree, tire vibration frequency under the external force and the natural vibration frequency of the tire is equal, the resonance occurs and "standing wave" happens. In the event of "standing wave" phenomenon, the vehicle will violently shake and the tire will burst with a sharp temperature increase, which is the most dangerous situation.
Vehicles are driven on wet road, if reaching a certain speed, between the tire and the ground the phenomenon of lubricating oil film same as sliding bearing will happen, moving vehicles are like inflatable boats floating on the water, this phenomenon is called "water cushion effect". When this happens, the adhesion between the tire and the ground drops sharply, and once the vehicle is exposed to the outside force, it deviates from its normal trajectory. At best spins happen, and at worst turn over takes place.
When the vehicle reaches a certain speed, if the tire's dynamic balance is not enough, it can cause steering wheel shaking and excessive wear. Low speed grade tire with bad dynamic balance if driven at high speed, this phenomenon will happen. Tires with Different speed grades have dynamic different balance accuracy.
For ordinary tires, speed level generally under 90 km/h (heavy truck tires allow maximum speed under 70 km/h), max. speed refers to sustained speed, not average speed. The longest sustained period is 1 h. Heavy vehicles mounted with regular tires are not suitable for long periods driving at high speed on the highway. Radial tires shall be applied. However, radial tire with the same size also has different speed rating specifications (S0 ~ 190km/h). Therefore, the radial tire must be selected according to the speed of the vehicle.
The mechanical property of the tire is also an important performance index of the tire, which mainly refers to passing through performance, cushioning performance and stiffness.
passing through performance mainly refer to two aspects, On the one hand, the smaller the tire diameter, the weaker the obstacle crossing ability of vehicle is, so the different diameter of the tire should be used to ensure the vehicle's obstacle crossing performance , on the other hand, when vehicles are driven on mud, snow and ice road, the adhesion between the tire and the ground is reduced, which can not provide enough driving force to guarantee the normal crossing and effective braking, therefore tires must have a reasonable structure, such as tire diameter, width and pattern, etc.
if the stiffness of the tire is not enough when turning (i.e., often said "soft"), the adhesion properties of the tire immediately becomes bad, the vehicle will appear under-steer, deviate from normal direction, this situation is the most dangerous for the high speed. Generally speaking, stiffness of wide tire is large, while stiffness of standard tire is small.
Tires must have good buffer performance, absorb vibration of the vehicle together with suspension frame , if the tire cushion performance is bad, it will not only affect vehicle comfort, but also affect the service life of other parts.
The tire will produce noise, tires with different structure and different pattern and at different speeds, the noise level will be different, and sometimes the noise will be annoying.
Do not mix old and new tires when mounting double tire on the same shaft. The new tire with larger diameter and the old tire with smaller diameter will cause severe overloading on the new tire while the old tire is under-loaded. The new and the old tires will not wear uniformly.
The tire of different sizes can not be mounted on the same axle. Tires of different sizes have different dia. Tires with big dia. are overloaded, tires with small dia. are under-loaded which will cause uneven wear.
the same pattern of tire shall be mounted on the same axle, otherwise, the adhesion of the two tires on the same axle will be different. Thus, the braking force deviation of the two side tires is too large, which will cause brake deviation.
The steering axle cannot be mounted with refurbished tire. Because of the poor adhesion between the refurbished layer and the old body, refurbished layer is easily rubbed off when the vehicle turns, and then lose the steering function and accidents occur. In addition, the plies of old tire often have hard injury, and flat tire easily happens, so refurbished tire cannot be mounted on the steering axle.
Different sizes have different inflation diameter and section width, the load distribution is different on the same axis, so the same sizes on the same axle shall be applied.
Radial tire cord are arranged perpendicular to the rim, the radial deformation is large, and cushioning performance is good. Belt ply is hard like a tank track, axial deformation is small, and rolling a circle is close to the length of the perimeter. However, bias tire is different, if tires of two kinds are mixed mounted on the same axis, the load is different, and the wear is not uniform.
It mainly refers to the material of the tire cord. The thickness of the carcass, the strength of the cord, the heat dissipation performance are different.
The ply grade is the load level of tire, if tires with different load capacity are mounted together, the inflation pressure is inconsistent.
The load is determined by ply rating and air pressure. Tires with same load capacity shall be used according to the conditions of loading and other conditions, so that the load performance is the same, which can prolong the service life of the tire.
If tire pattern is different, not only the wear, but also ground adhesion if different..
Different manufacturers have different tire size, tread width, pattern shape and cord material. Mounting tires of different manufactures can also affect the use effect. Tires from the same manufacture shall be mounted on the same axis.