How to view the basic parameters of the wheel

Size:
The size of the wheel hub is commonly referred to as 15 inches, and 16 inches refers to the size of the wheel hub, which is the diameter.
The larger the size of the wheel hub, the more stable the vehicle's handling will be, but with it comes the issue of additional fuel consumption. There is an approximate reference value. The Unsprung mass 1KG=vehicle weight 10KG. The smaller the Unsprung mass, the smaller the weight load on the wheel rotating axle. From a physical perspective, the larger the mass of an object, the greater the force required to move it from rest to motion. When applied to the car, the lighter the Unsprung mass is, the shorter the stationary starting time is. When modifying, the material and weight of the wheel hub will be optimized first. At present, the aluminum alloy forging process can effectively improve the strength of wheel hubs and reduce weight. Four wheels can reduce the weight by more than 10KG.
Components belonging to Unsprung mass include: spring, shock absorber, upper and lower arms, half axle, steering tie rod, connecting rod, brake caliper, brake disc, sheep horn, tire, wheel hub, etc.

The wheel hub and tires are still missing in the picture. The impact of tire size on sedans:
Firstly, it's not just about the diameter of the wheel hub, but about the diameter of the wheel hub with the tires installed. The bigger the tire, the smaller the acceleration, and the greater the noise will be. However, the greater the grip area, the better the stability will be, and the range of Braking distance will also be reduced. The brake pad loss will also be increased. At the same time, the fuel consumption will be higher. After the size is larger, the tire will also be correspondingly flatter, and the damping effect will be weaker, unless the manufacturer has adjusted the damping parameters for the flat tire. So, the larger the size, the better. If you choose a large wheel hub for modification, it is recommended to choose a better quality brake system.

When modifying, the first reason for the wheel hub modification is to reserve space for the brake pump. Many original cars would not have enough space if they were to replace a better quality brake system.

In addition, selecting the wheel hub also requires matching the J value and ET value to achieve a plump effect that is flush with the fender. Width (J value), commonly referred to as 7J, where the number represents the width of the wheel hub, while J only represents the shape and height of the wheel hub flange. In addition to J, there will also be C, JJ, JK, K, etc. The main difference lies in the height. C is the lowest, K is the highest, and J is the most common hub type.

If the wheel hub is increased by one inch, such as from 7J to 8J, the width of the wheel hub will be 25.4mm. This value needs to match the ET value to achieve a flush effect with the fender.

The recommended dimensions for the width of the wheel hub and the tread width are. Offset, also known as ET value: ET comes from German EinpressTiefe, which literally means "depth of indentation". The smaller the offset, the more the wheel hub will deviate from the outside of the vehicle after installation. The unit of wheel hub offset (ET) is mm, which refers to the distance from the centerline of the wheel hub to the installation surface. Assuming that the offset of the new wheel hub is 54mm, while the offset of the original wheel hub is 51mm, the new wheel hub will retract 3mm inward after being sleeved.

The deviation between the surface of the wheel hub installation and the centerline of the wheel rim. There are three types: positive, zero, and negative.

Changing the ET value of the wheel hub will change the track width of the car, thus affecting the load on the bearings. At the same time, during the modification process, it is also necessary to consider the impact of the ET value on the brakes.

So, the ET value here needs to be selected as an appropriate value. Here, it is necessary to know the gap distance between the wheel hub and the fender (as shown in the figure). Generally, there is an additional 20-30mm for vehicles. So, after selecting the J value of the hub, according to the actual situation, reduce the ET value to achieve a full edge effect. PCD and hole position PCD are the pitch diameter, which refers to the diameter between the fixed bolts in the center of the wheel hub. And for the whole position, the general wheel hub hole position is 4-5 bolts, and the distance between the bolts is also different. It is often heard that 5 * 112 refers to 5 bolts, and the PCD is 112mm. For safety reasons, it is recommended to replace the wheel hub with the same one as the original factory for renovation and upgrading.

Example:

Center hole: The center hole is the part used for fixed connection with the vehicle, which is the position of the hub center and the concentric circle of the hub, as shown in the above figure. This diameter directly affects whether the hub fits with the Centroid. If the center hole is too large, the center reducing ring can be used to achieve a perfect fit.