How to Choose a Tire

Security, economy, and comfort of vehicle are related with reliability, rolling resistance, adhesive capacity and cushioning performance of tire respectively. Therefore, there are strict regulations on the tire specifications for various vehicles. When changing the original tire on the vehicle, special attention shall be paid to the characteristics of the tire structure, level or load index, speed rating, tread pattern, etc. To change all the tires of the whole vehicle is convenient and trouble saving, but increases the cost to use. Most of organizations and individuals all adopt the method of changing the original tire one by one, which causes there are new and old tires on the vehicle at the same time. Therefore, when changing tires, remember to ensure the same outer diameter, level and tread pattern of all the tires. Generally, if performance of tires between the left and right wheels on the front axle is different, it’s easy to lead to deviation of direction and braking; if outer diameters of the internal and external gear tires on rear axle are different, it’s likely to cause overload of single tire. Now, transport enterprises usually have various vehicles in different specifications, complicated vehicle types and many tire specifications, and use bias tires and radial tires.  When assembling tires, “Eight Sameness” shall be realized on the same axle of an automobile:

①The same specification: Tires of different specifications have different inflatable outer diameters and section widths. When they are assembled on the same axle, different loads will be distributed on them. It is required that tires on the same axle shall have the same specification. Besides, the vehicles without special requirements on the front and rear axles, tires on them shall have the same specification.

② The same structure: Cord thread of radial tire is vertical to the tire rim in arrangement, and the tire is featured by large radial deformation, good cushioning performance, and solid belted layer (like tank track), so circumferential deformation is small. When the tire rolls a circle, it is close to the length of the outer perimeter. However, it is different for the bias tire. It is featured by small radial deformation and weak cushioning performance. The part contacting with road in driving is compressed, so its circumferential deformation is large and when the tire rolls a circle, it is shorter than the length of the outer perimeter. When assembling the two different kinds of tires on the same axle, they bare different loads and wear inevitably. Therefore, tires of the same structure shall be assembled on the same axle.

③The same material: It is mainly refers to cord thread used by the tire body. For example: For the full steel radial tire and fiber radial tire, there are great differences in the thickness of the tire body, cord thread strength, heat dissipation, etc., and mixed assembling of them will influence the use effect. Therefore, the cord thread material for the tire body (also called framework material of the tire body professionally) on the same axle shall be the same.

④The same level: Level means load level of the tire and it determines the relevant pressure standard. Tires with different load capacities have different inflation pressure and deformation. Therefore, tires on the same axle shall be in the same level so as to ensure the tires have the same load.

⑤The same tread: Different tire tread has different wear limit and different adhesion to road. If tires on the left and right wheels have different treads (for example, tires with vertical and horizontal treads are assembled on the same axle), it will influence smoothness of the automobile and brings uneven wear and drift in emergency braking.

⑥The same brand: Tires made by different manufacturers have different wheel sizes, tread widths, tread shapes and cord thread materials somehow. Mixed assembling of tires of different brands also influences the use effect. Tires on the same axle shall have the same brand so as the vehicle and tires have their due performance.

⑦The same pressure: Pressure depends on the level. Tires in the same level shall have the same pressure. So tires on the same axle shall be the same in pressure.

⑧The same load: Load depends on the level and pressure. Tires with the same load capacity shall be assembled according to the use conditions of load, which prolongs service life of tire. Therefore, tires on the same axle shall be the same in load capacity. Taking 10.00R20 16PR full steel radial tire for example, it is clearly defined in the national standard that when the pressure is 850kpa, its load capacity is 3,150kg; when the pressure is 770kpa, the load capacity is 2,800kg. It indicates clearly in the above regulation that level and pressure determine the load capacity.

When driving the vehicle in specific conditions, there are specific requirements on the tire. After the tire is used, mended and renovated, its performance decreases and is only suitable for some certain use conditions, so tires shall be selected and assembled. Better tires shall be assembled on the front axle or vehicles used in long distance transportation and regularly continuous driving for higher safety; used tires shall be assembled on the rear axle; mended and renovated tires shall be assembled on the rear axle of the vehicle used in short distance transportation, slow driving speed and light load; for the vehicle that usually drives on soft and muddy road, it shall be assembled with tires with horizontal tread or deep remaining tread depth to prevent slipping; for vehicle that usually drives on the road full of rocks and hard objects, the rear axle shall be assembled with used, mended or renovated tires to reduce loss caused by pricking and scratching; in summer, tires warm quickly so the front and rear axles shall be assembled with good tires to prevent tire burst in high temperature; in winter, tires warms slowly so vehicles are assembled with inferior tires because temperature is low. Conflict between driving requirement of vehicle and tire characteristic can be well solved by reasonable assembly.