Getting Started with Car Modification (Wheel Hub Edition)

This article is a summary of my car wheel modification journey, from being an armchair expert to hands-on practice, from a novice to a beginner in car modification. It is suitable for car enthusiasts who are planning to modify their cars or are just starting out like me. At the same time, guidance from senior experts in the modification industry is highly welcome.

This article is divided into two parts: • Basic knowledge of wheel hubs • How to choose suitable modified wheel hubs

I. Basic Knowledge of Wheel Hubs
A car wheel hub refers to the rotating part of the wheel core connected by uprights inside the tire contour, that is, the metal component mounted on the axle that supports the tire. Its functions are to support the tire and transmit power.

Most wheel hubs currently are mainly made of aluminum alloy. Aluminum alloy is not easily deformed, has high strength and light weight. With the continuous progress of aluminum manufacturing technology, the cost is getting lower and lower, and more and more cars are equipped with aluminum alloy wheel hubs. This article mainly focuses on aluminum alloy wheel hubs. Low-end models may still have iron wheel hubs. Iron wheel hubs are cheaper than aluminum alloy ones, but they are heavier for the same size, and are more prone to deformation and damage when impacted, so they are gradually being replaced by aluminum alloy ones. At present, the most cutting-edge carbon fiber wheel hubs are still far beyond our reach.

(I) Wheel Hub Manufacturing Processes
There are two main types: casting and forging, among which casting is further divided into gravity casting and pressure casting. The following is an introduction from the lowest-end to the highest-end.

Gravity Casting: Pour the aluminum alloy solution into the mold, and after forming, process and polish it on a lathe and then spray it. The advantages are simple manufacturing, low cost and low scrap rate. The disadvantage is that sand holes or bubbles may form inside the material, resulting in uneven density and affecting strength. Therefore, this type of wheel hub is generally made relatively heavy, and the shape is not very attractive (more material is used to ensure strength, and simple patterns are used to save costs). It is commonly used in mid-to-low-end family cars.

Pressure Casting: After pouring the aluminum alloy solution into the mold, apply a certain pressure, and then polish and paint it after forming. The advantages are that it can achieve high strength and light weight while controlling costs, and the scrap rate is within an acceptable range, so it has a very high cost performance. Different manufacturers also have their own unique pressure casting methods, such as low-pressure casting, spin casting, etc. Pressure-cast wheel hubs are original-equipment wheel hubs for many mid-to-high-end cars, and are also widely used in modifications, representing good quality at a reasonable price.

Forging: Use a forging press to apply pressure to the metal blank to form it. The advantages are high strength and light weight. The disadvantages are that it has little toughness and is prone to direct fracture under strong impact. In addition, the yield rate is low and the price is high. The quality of forged wheel hubs depends on two aspects: on the one hand, the quality of the metal blank, and on the other hand, the quality of the forging press. Forging presses are divided into 10,000-ton forging and 1,000-ton forging. Generally, the forging quality of large factories is guaranteed.
If they are genuine wheel hubs from large factories, the ranking by manufacturing process is roughly as follows: High-end forging > low-end forging ≧ high-end pressure casting > low-end pressure casting > gravity casting

(II) Wheel Hub Parameters
Wheel Hub Size: It is the diameter of the wheel rim, measured in inches. Generally, the larger the car, the larger the wheel hub. For B-class cars, 17-inch and 18-inch wheel hubs are more common.
Wheel Hub Width (J Value): The distance between the flanges on both sides of the wheel hub is the width of the wheel rim, which is generally expressed by a number + J. 8J = 8 (inches) x 25.4 (1 inch = 25.4mm) + 2 (the wheel hub has two flanges) x 15.7 (the width of the flange, which is also the width of J) = 234.6mm. Generally, you can choose the tire according to the comparison table.
Offset (ET Value): The distance from the mounting surface of the wheel hub to the center line of the wheel hub. This is very important during modification!
When choosing a wheel hub with a different ET value from the original one, it will more or less affect the kingpin offset and change the original suspension state of the vehicle. I will not go into depth here (I don’t know much about this aspect either). If possible after modification, you can ask a professional to adjust it to try to maintain the original suspension state of the vehicle.

As can be seen from the above figure, the intersection of the two dashed lines is exactly in the middle of the contact surface between the tire and the road surface. Of course, not all original vehicles of group friends are like this.

The offset also affects brake modification to a certain extent. Without enough space, large calipers cannot be installed. 4. Bolt Pattern: It refers to the number of wheel hub fixing screws and the diameter of the circle formed by the centers of the screw holes. It should be noted that the bolt patterns of cars of different brands and levels are different. For A-class cars, there are 4×100, 5×100, 4×120, etc. Japanese midsize sedans are mostly 5×114.3, German cars are mostly 5×120, 5×112, and American cars have various types. When buying a wheel hub, you must figure out the bolt pattern of your vehicle. 5. Center Bore: The diameter of the car axle head and the inner diameter of the wheel hub inner hole. Generally, modified wheel hubs are 73.1mm, which is larger than the center bore of all manufacturers, so an adapter ring is required during installation. The center bore of each manufacturer is different, so you must confirm the size during modification. In addition, it is better to buy forged aluminum adapter rings, which are available on Taobao, and they are generally very expensive in offline stores.

The circled part is the adapter ring

II. How to Choose Suitable Modified Wheel Hubs
(I) Clarify Your Own Needs
Everyone’s purpose of modification is different. Some want to improve the appearance of the vehicle, and some want to improve performance. People also have different preferences for modification styles, such as JDM style, low-rider style, and various other modification styles. Having no purpose or idea is a big mistake. If a guy wants to modify his car, goes to a modification shop, and says to the clerk “just make my car look good”, then it’s okay if he meets a knowledgeable master, at most he spends a little more money. But if he meets someone who likes the bosozoku style, then he will lose both his car and money. I only talk about wheel hubs here, not other aspects.

Bosozoku style

(II) Selection of Wheel Hubs
Selection of Wheel Hub Brands and Their Pros and Cons (1) International Big Brands German-made BBS, Italian OZ, Japanese BBS, Japanese Rays, Japanese Work, Japanese SSR, Japanese ADVAN, Japanese Enkei, etc., as well as some American brands (I don’t know much about them) and brands that are not well-known in China, such as Japanese AME, Taiwan BC, etc.
The only disadvantage of big-brand wheel hubs is that they are expensive. In terms of quality, as long as they are genuine, properly matched and installed correctly, there are basically no problems. When encountering ordinary bumps, the probability of fracture is very small. It should be clearly stated that when driving at high speed and hitting stones or large potholes, if the wheel hub is deformed or damaged, as long as the four wheels are intact, the braking force and handling will not be lost too much. This is exactly the manifestation of good wheel hub quality. If the wheel hub breaks directly and becomes a three-wheeled vehicle, the car will most likely lose control directly.

Not everyone is Schumacher

Big-brand wheel hubs are more sophisticated in design. For example, Rays’ TE37 series, ADVAN’s GT series, OZ’s Superturismo series, etc. These classic models ensure good appearance and have been verified by various auto races. When designing, the stress conditions under different driving conditions are considered, and the structural strength is optimized while achieving extreme light weight (99.9% of modification players cannot drive with the intensity of WRC). They are also at the international top level in manufacturing technology. It is said that the spin casting of Enkei is better in quality than domestic forging. Moreover, wheel hubs produced by big brands will pass various certifications, generally including Japanese VIA or German TUV certification.

WRC car using OZ wheel hubs

Generally speaking, if you don’t care about the money, you can blindly choose big-brand wheel hubs!

Another point is that the second-hand value retention rate of classic big-brand wheel hubs is quite high. However, if you buy second-hand ones, there are still many pitfalls. First, there are a lot of counterfeits, and it is difficult to distinguish between genuine and fake. If you want to buy second-hand ones, it is very important to find an experienced person. Second, it is not easy to identify the condition of the wheel hub. No wheel hub is absolutely round. Only after installing the tire and doing a wheel balance can you see the condition clearly. (2) Domestic Big Brands For customized wheel hub modification, please contact Ningbo Jianglu Auto Parts Industry and Trade Co., Ltd., which produces one-piece, two-piece and three-piece customized forged wheel hubs. Customization services for color, design and wheel hub covers are available. 2. Selection of Wheel Hub Styles (1) Performance-modified Wheel Hubs: BBS-RID/FID, Rays-TE37, SSR-type C/F, ADVAN-GT, etc. These have been verified by various races, and performance players can just buy them. (2) Appearance-focused Modified Wheel Hubs: BBS multi-piece forged, Work customized forged, Enkei multi-spoke, etc. As long as they are genuine products from regular brands, combined with your own modification style, you can choose the wheel hub freely. Generally, you can increase the size by at most 2 inches, and increasing by 1 inch is a more balanced choice. The rest depends on your own preference.

I hope everyone can enjoy car modification and driving, with driving safety first, civilized driving second, and enjoying the fun third.

May 7, 2026