Page 25 - 《橡塑技术与装备》英文版2025年12月

NEW TECHNOLOGIES AND PRODUCTS

Table 1 Design indicators thickness, while an increase in b value will increase tread width
Project Design Requirements and shoulder thickness.
Standard rim 8J
Inflated outer diameter (mm) 669（663-675） The radius of curvature of the running surface is related
Inflation section width/mm 236（227-243） to the tire aspect ratio and the rigidity of the belt layer. The
Standard inflation pressure / kPa 250
Standard load / kg 670 larger the radius, the smaller the curvature height, and the
Speed level Y
Pattern type Asymmetrical pattern wider the running surface width.
Product weight / kg 10.9 To ensure the maximum ground contact area between
Rolling resistance ≤6.5 (enterprise standard)
the tire and the road surface within the width of the running
The core difference between electric vehicles and surface, it is generally advisable to set h/H to a value between
conventional cars lies in their energy systems, while their 0.03 and 0.08. The ratio of the running surface width b to the
usage conditions and vehicle designs are essentially identical. section width B, denoted as b/B, is generally recommended to
Given the similarities in driving conditions and vehicle be between 0.7 and 0.85. In this design, b is set to 194 mm, h
dynamics between electric vehicles and conventional cars, to 7.801 mm, H to 100.65 mm, h/H to 0.077506, and b/B to
this design adopts the technologically mature semi-steel radial 0.766798.
tire structure system and optimizes it for the characteristics 2.4 Position of horizontal axis of section (H 1 /
of electric vehicles. The outer edge dimensions of the tire H 2 )
after inflation serve as the basis for design. The belt layer of The horizontal axis of the tire section is the horizontal
radial tires exhibits extremely strong circumferential rigidity, auxiliary line at the widest point of the tire section, and its
effectively constraining the expansion of the tire body, position is represented by the ratio H 1 /H 2 . This parameter has
resulting in a small expansion rate (D/D) of the outer diameter a significant impact on tire performance: when H 1 /H 2 < 1, the
after inflation. The change rate of the B value is slightly greater high-speed performance of the tire can be improved; when H1/
than that of D, and the selection of the B value is closely H2 > 1, the tire has superior load-bearing capacity. Considering
related to the bead contact width (c). Based on our company's that electric cars often need to travel at high speeds, and based
similar product design experience and existing production and on the company's design experience, H 1 /H 2 is set to 0.952473
construction conditions, the specific values are as follows: in this design to ensure stability under high-speed conditions.
D́=669 mm, D́/D́=1.010 574, D=662 mm 2.5 Bead fit diameter d
B́=236 mm, B́/B́=0.932 806 B=253 mm The design of the bead seating diameter (d) requires
2.2 Bead fit width C a balance between the convenience of tire assembly and
The C value of a passenger car radial tire directly affects disassembly and the tight fit between the bead and the rim.
the contour shape of the tire section, the force distribution Generally, the bead seating diameter corresponding to a flat-
on the sidewall, and the final performance. When selecting, base rim should be 1~3 mm smaller than the rim diameter. If
comprehensive considerations should be made from aspects the fit is too loose, it can easily lead to movement, deformation,
such as the offset of the horizontal axis of the section, changes and even tire blowout risks during tire operation. To avoid such
in the rigidity of the sidewall, and usage factors of the tire. The issues, d is set to 460.7 mm in this design to ensure a stable fit
aspect ratio of the tire is the "primary benchmark" for selecting between the bead and the rim.
the C value, so it is selected based on the aspect ratio of the 2.6 Tread pattern design
tire. In this design, the C value is set to be 25.4 mm larger than The tread pattern primarily features four longitudinal
the standard rim width, taking it to be 228.4 mm. straight grooves, effectively enhancing drainage and heat
2.3 Running surface width b and camber h dissipation capabilities. Additionally, transverse grooves are
The tread width b and camber h are key parameters that incorporated to increase friction between the tire and the
determine the tire's ground contact performance: a decrease in ground, thereby improving grip performance. The overall
b value will result in a reduction in tread width and shoulder pattern adopts a closed shoulder strip design, with a pattern

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