Nominal section width and section width When explaining the figure of tire width, we need to understand two terms first? Nominal section width and section width. Nominal section width: generally speaking, it is the theoretical value of the optimal design width, which is equivalent to the official fuel consumption of the car. Both fluctuate up and down this value. Because our tires are all composed of rubber, cord and steel wire, these tire components have fixed standards and values in production, and the tire width calculated according to these standard values belongs to the nominal section width.
Section width: the section width we are talking about is the actual value of measuring the section width of the tire. However, due to certain tolerances in the production process, there will be some errors between the calculated section width and the actual section width, but the errors must be within the scope of national standards.
Nominal diameter of hub: The nominal diameter of hub refers to the 17 inch or 18 inch hub in our life, and these refer to the tire diameter of hub. The precision of this diameter is relatively high, and the error of the whole circumference should not be higher than 0.5mm, but the unit of size is inches. The actual diameter is 24mm larger than the nominal diameter in the production process, so the actual diameter of a hub = nominal diameter x 25.4 mm+.
The specifications of tires need to be unified, which is convenient for manufacturers to produce and consumers to buy tires. In the production process, due to the tolerance of components, the actual width of the finished tire will fluctuate after the production is completed. For example, the marked width of the tire is 205mm, and in the actual production process, the actual section width may be 202 or 206. If the actual production width is taken as the standard, the tire size will become infinite, such as 2000.
From the manufacturer's point of view, the more tire sizes, the more output, which will greatly increase the pressure of production; When it comes to sales, the complexity of tire models means that more goods are needed, which is very stressful for ordinary businesses; Finally, it will go to consumers, so that consumers can't start.
When many tires are designed, considering the protection of the hub, the rim of the tire will protrude from the hub. In this case, the nominal width of the tire has not changed much, but the actual width has greatly increased. For example, Deng Lupu R 1 model 205/55/ 16 has the rim protection function, so the rim of the tire is higher than the hub. In this case, the actual width of the tire is higher than other tires of the same model, but it is also installed on the hub of 15 inch, so a standard is needed at this time to make it easier for consumers to distinguish. The most compromised number is 5, so all tire width values end with 5.
Another parameter that determines tire width, J value. After introducing the tire width, let's take a look at this parameter, and the j value represents the range of tire width that can be installed. The value of j is determined by the width of the hub, which refers to the distance between the protrusions on both sides of the hub. Generally speaking, J is the most common, along with C, JJ and JK. The main difference is that the height of the hub edge is different. J value determines the width of the hub, and the width of the hub determines the width of the tire, so we need to
Conclusion The tire width ends with 5, mainly to avoid the tolerance problem in the tire production process, as mathematically said, it is about equal to, although it is different from the actual width, it will not affect the driving safety in the use process. On the contrary, we assume that if it is produced and defined according to the actual width, the produced tire model will show geometric growth due to the difference of tire width, size and flattening rate. It will have a great impact on our use, so we need a compromise at this time, that is, about equal to, and the most suitable number in about equal to is 5, so 5 exists in all tire width values.