Complete analysis of wheel hub modification: from parameters to selection

In the field of automotive modification, wheel hub modification is a highly anticipated project. It can not only refresh the appearance of the vehicle and highlight the unique personality of the owner, but may also have a certain impact on the performance of the vehicle. However, wheel hub modification is not a simple "replacement", it involves a lot of professional knowledge and key points, and should be treated with caution.

1、 Basic parameters of wheel hub, the basis for modification

（1） Wheel size
Wheel size refers to the diameter of the wheel hub, commonly expressed as 17 inches, 18 inches, etc. Under the regulations of our country, wheel hub modification generally cannot change the size, only the style and color. If you want to upgrade the wheel hub size, you must strictly follow the principle of not exceeding 2 inches of the original wheel hub. Increasing the size of the wheel hub can make the vehicle visually more impactful and improve driving stability, but at the same time, it may reduce the tire flatness ratio, decrease shock absorption performance, compromise comfort, and may also increase fuel consumption. For example, vehicles that were originally compatible with 16 inch wheels, blindly upgrading to 19 inch wheels, will significantly increase the bumpy feeling when passing through speed bumps or bumpy roads.

（2） Wheel hub width (J value)
The width of the wheel hub is expressed in J values, such as 6J, 7J, etc. The J value determines the range of tire widths that can be installed on the wheel hub, and different J values correspond to different optimal tire widths. For example, the tire width compatible with a 6J wheel hub may be between 185-205mm. Choosing wheels with appropriate J values is essential to ensure stable tire installation and fully utilize performance. If the J value is too high, the tire may not be securely installed; If the J value is too small, the tire cannot be installed properly. If tires that do not match the J value are used, such as large J values with small tire widths, it will widen the tire surface, reduce driving comfort, increase tire noise, deteriorate road filtering ability, and decrease stability.

（3） PCD (pitch diameter)
PCD refers to the diameter of the circle formed by the central fixing bolt of the wheel hub, measured in millimeters. For example, the common 5X114.3 represents a wheel hub with 5 bolt holes and a pitch diameter of 114.3mm. The PCD value determines whether the wheel hub can be installed on the vehicle axle head. If the PCD of the new wheel hub is different from that of the original vehicle, a flange can be added within a safe range to achieve normal installation, but this requires professional operation, otherwise it may cause safety hazards.

（4） CB (center hole)
The central hole is a circular hole at the center of the wheel hub, and its size must match the size of the vehicle axle head. The central hole can only be just right or larger. If the diameter of the central hole is large, a variable diameter ring can be added for adjustment; If the diameter is small, the hub cannot be used. If the center hole does not match, the vehicle will shake while driving, affecting driving stability and safety.

（5） ET (offset)
Offset distance is the distance from the centerline of the wheel hub to the mounting surface of the wheel hub, measured in millimeters. The original offset value of most cars ranges from 35-50mm. The smaller the ET value, the more outward the wheel hub protrudes; The larger the ET value, the more the wheel hub shrinks inward. When modifying, choosing wheels with a similar offset value to the original factory can avoid interference with the body and steering system. For example, if the ET value is too small, the wheel hub may rub against the fender or suspension components during vehicle operation, affecting driving safety.

2、 Consideration of Wheel Material, Performance, and Cost

（1） Steel wheel hub
Steel wheel hubs have low cost and high strength, making them suitable for use in some vehicle models with strict cost control and the need to withstand large loads, such as some commercial or engineering vehicles. However, its poor heat dissipation is not conducive to heat dissipation during high-speed driving or frequent braking, which may affect braking performance. At the same time, steel wheel hubs are prone to corrosion, which can affect their appearance after long-term use, and their heavy weight increases the unsprung mass of the vehicle, which is not conducive to improving its handling and fuel economy.

（2） Aluminum alloy wheels
Aluminum alloy wheels are lightweight and can effectively reduce the unsprung mass of vehicles, improving handling performance. It has high strength and can meet the needs of daily driving and some high-performance driving. Excellent heat dissipation performance ensures that heat is quickly dissipated during vehicle braking, maintaining the stability of the braking system. At present, the majority of household cars in the market are equipped with aluminum alloy wheels from the original factory. Aluminum alloy wheels with different forging processes have differences in strength and aesthetics. For example, aluminum alloy wheels produced by low-pressure casting have relatively lower costs, but may not be as strong and lightweight as forged aluminum alloy wheels.

（3） Carbon fiber wheel hub
Carbon fiber wheels have the characteristics of extremely light weight and high hardness, with excellent performance in various aspects, which can greatly improve the handling and acceleration performance of vehicles. However, due to its complex production process and high cost, it is currently mainly used in some high-end sports cars or racing fields, and is relatively rare in the ordinary household car market.

3、 Wheel hub technology, quality assurance

（1） Casting process
Casting is divided into gravity casting and low-pressure casting. Gravity casting is the process of pouring liquid metal into a mold and using gravity to fill the mold into shape. The process is simple and cost-effective. However, this process can easily generate voids and bubbles inside the material, resulting in uneven density and affecting overall strength. Low pressure casting is the process of injecting liquid metal into a mold under low pressure conditions. Compared to gravity casting, the product quality has been improved, but there are still some internal defects. Wheel hubs produced by casting technology are widely used in the mid to low end market.

（2） Spinning casting process
Spinning casting is an improvement on the basis of casting, which uses spinning equipment to process the wheel hub blank, making the internal structure of the wheel hub denser and improving its strength during the forming process. Compared to ordinary cast wheels, spin cast wheels are lighter and harder, with certain improvements in performance and quality, and are relatively affordable, gradually gaining popularity among consumers.

（3） Forging process
Forging wheel hubs is achieved by applying immense pressure to aluminum alloy billets to shape them in molds. The wheels produced by this process have extremely high strength, light weight, and can withstand extremely high loads, making them suitable for use in high-performance vehicles. High horsepower performance cars, new energy vehicles, and large SUVs with high requirements for wheel hub performance often choose forged wheels. However, the high cost of forging technology results in expensive forged wheel hubs, but they still have great appeal for consumers who pursue ultimate performance and quality.

4、 Wheel hub style, showcasing individuality

（1） Less spoke/hollowed out style
This type of wheel hub design is simple and has a strong sense of sportiness, which can effectively reduce the weight of the wheel hub and improve the handling performance of the vehicle. It is very suitable for sports cars or models that pursue individuality and focus on handling experience. Its unique design can display a strong sense of dynamism and speed when the vehicle is in motion, attracting a lot of attention.

（2） Multi spoke style
Multi spoke wheels give a full and steady feeling, with strong tension. This style is suitable for business style or models that pursue low-key luxury, and can add a sense of grandeur and elegance to the vehicle. In some luxury cars, the application of multi spoke wheels is more common, highlighting the high-end quality of the vehicle.
When making wheel hub modifications, car owners need to consider multiple factors such as regulatory requirements, personal needs, vehicle performance, and budget, and carefully choose the appropriate wheel hub. At the same time, it is recommended to choose a professional modification shop for installation to ensure the safety and standardization of the modification process, so that the car can achieve dual improvement in performance and appearance under the premise of legal compliance.