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Rims and hubs are two key but functionally distinct components in the wheel system. As the core supporting structure of the wheel, the hub is located in the central area and connects the axle to the wheel through the central hole, bolt holes, and spokes. It mainly functions to transmit power, bear the weight of the vehicle body, and assist in brake heat dissipation. Its materials are mostly aluminum alloy or steel, with various shapes that directly affect the vehicle's exterior design. The rim is the annular metal ring on the periphery of the hub, which directly contacts the tire bead. It fixes the tire and maintains tire pressure sealing performance through a 46-degree inclined flange design. Its width parameter (J value) must be strictly matched with the tire specification to ensure safety. In terms of damage characteristics, common problems with hubs are impact deformation or cracking, while rims are more prone to edge dents or slow air leakage due to rust caused by high-speed pothole impacts. During maintenance, slight deformation of the hub can be corrected, but cracking requires replacement. If the sealing surface of the rim is damaged, it is recommended to replace it directly. When modifying, attention should be paid to the consistency of the hub's PCD value and central hole diameter with the original vehicle, and the rim width should be adapted to the tire specification. Blind widening may pose a risk of tire blowout. Although the two are often confused, structurally the hub is the "skeleton" and the rim is the "outer ring", which together form a complete wheel unit. Correctly distinguishing between them is crucial for vehicle maintenance and modification.

The main differences between belt-driven and direct-driven wheels lie in their power transmission methods and mechanical structures. The belt-driven system connects the motor and wheels via an elastic belt, which incurs transmission losses and requires regular maintenance (such as belt replacement), but it has lower cost and mature technology, making it suitable for consumers with limited budgets. The direct-drive system, on the other hand, adopts a design where the motor is directly coupled with the wheel axle, eliminating intermediate transmission links. It boasts higher energy efficiency (with a transmission efficiency of over 98%) and quieter operation, while also reducing mechanical wear. Over long-term use, it can save approximately 15%-20% of electricity, but its initial purchase cost is 30%-40% higher than that of the belt-driven system. In terms of durability, the bearings of the direct-drive system have to bear greater loads, whereas the belt-driven system extends the motor's lifespan through physical buffering but requires belt replacement every 3 years. If quietness and energy efficiency are prioritized, the direct-drive system is recommended; if economy and ease of maintenance are given top priority, the belt-driven system is more suitable.

The axle is a core component of a vehicle's transmission and load-bearing system, whose main functions are to connect the wheels, transmit driving force and braking force, and support the weight of the entire vehicle. It can be divided into four types according to the driving mode: steering axle, drive axle, steering drive axle, and support axle. The steering axle enables wheel deflection through the swing of the steering knuckle, performs the steering function and bears vertical loads, and is commonly found in the front axle of front-wheel-drive vehicles. The drive axle is responsible for transmitting engine power to the driving wheels, including components such as the main reducer and differential, and is mostly used in the rear axle of rear-wheel-drive vehicles. The steering drive axle has both steering and driving functions, with a complex structure, and is mainly applied in all-wheel-drive off-road vehicles. The support axle is a driven axle that only bears the load, such as the rear axle of front-engine front-wheel-drive sedans or the non-driving rear axle of three-axle vehicles. In terms of suspension structure, axles can also be divided into integral axles (matched with non-independent suspension) and disconnected axles (matched with independent suspension); the former is rigidly connected, while the latter improves driving stability through movable joints. Daily maintenance requires regular inspection of bolt tightness, lubrication conditions, and the braking system. It is recommended to replace the gear oil and adjust the toe-in every 3,000 to 5,000 kilometers to ensure driving safety and component lifespan.

The "+35" marked on the wheel hub indicates that the ET value of the hub is +35 millimeters, meaning the offset between the hub's mounting surface and the rim's centerline is 35 millimeters inward. The ET value (Offset) is a key parameter for determining the hub's mounting position: a positive value indicates the mounting surface is oriented toward the vehicle's inner side, while a negative value indicates an outward orientation. The ET value of original equipment (OE) passenger car hubs typically ranges between 35 and 50 millimeters; +35 represents a moderately small positive value. This design causes the hub to protrude slightly outward, improving visual impact and cornering stability. However, modifications must account for the J value (hub width), tire dimensions, and suspension geometry. An excessively small ET value (e.g., +10) may achieve fender-flush alignment but could increase steering effort and reduce bearing service life. For modifications, select hubs with ET values approximating OEM specifications or perform professional calculations to ensure compatibility among tires, suspension components, and braking systems, thereby preventing abnormal wear or clearance issues.

The layout of the drive wheels has a direct impact on vehicle handling. Front-wheel drive (FWD) and rear-wheel drive (RWD) differ significantly in power distribution, steering characteristics, and dynamic performance. In FWD vehicles, the engine and transmission are concentrated on the front axle, resulting in a heavier front end. This makes them prone to understeer (plowing) when cornering at high speeds, but they are easier to handle in daily driving, more fuel-efficient, and suitable for family sedans. Their compact structure also improves the utilization of interior space. RWD vehicles, on the other hand, transfer power to the rear wheels via a driveshaft, leading to a more balanced front-to-rear weight distribution. During acceleration, the weight shift to the rear enhances rear-wheel traction, making them better at climbing hills and maintaining straight-line stability. However, they are prone to oversteer (tail-sliding) on wet or slippery roads and require more advanced driving skills, which is why they are commonly found in performance cars or luxury models. Additionally, FWD vehicles exhibit more pronounced "nose-diving" during braking due to the concentrated components at the front, while RWD vehicles offer more responsive handling during spirited driving but incur higher maintenance costs. When making a choice, one needs to balance handling requirements and usage scenarios—for example, FWD is preferred for urban commuting, while RWD can be considered for those seeking driving pleasure.