The J value of a wheel rim refers to its width. Generally speaking, the wider the wheel rim, the larger the J value. High-performance vehicles tend to have wider rims, resulting in a larger contact area with the ground. This increases the vehicle's grip, preventing it from slipping due to excessive torque. Additionally, wider rims provide better braking performance because the increased contact area with the ground enhances friction.
Different J values require corresponding tire widths. For example, a wheel rim with a "6.5" J value corresponds to a tire width of 205 millimeters, while a rim with a "75" J value corresponds to a tire width of 225 millimeters.
Other Wheel Rim Specifications:
ET (Offset): ET is the abbreviation for the German term "Einpress Tiefe," which means "insertion depth," measured in millimeters. For example, "ET 25" indicates that the wheel rim has an insertion depth of 25 millimeters. Generally, the smaller the ET value, the more the wheel rim protrudes outward.
The ET value serves two main purposes. First, it helps to avoid contact between the brake and the suspension. If the rim is relatively wide, the inner side of the rim may touch the suspension, so reducing the ET value can allow the rim to extend outward. Additionally, the ET value helps stabilize the vehicle's body, ensuring that there is no lateral movement even when accelerating through a curve. However, it is recommended that drivers avoid attempting curve acceleration.
PCD (Pitch Circle Diameter): PCD refers to the bolt pattern of the wheel rim, also known as the pitch circle diameter. For instance, in values like "5112" or "5114," the "5" represents the number of bolts needed to secure the rim, while "112" and "114" are the pitch circle diameters of the rim.
