The BMW five-series door is made of iron. The car door made of this material has light weight, sufficient strength and rigidity, good anti-collision performance, good sealing performance, convenient opening and closing, stable and reliable driving, and is safe and reliable.
The wheel hub size of BMW 5 Series car is 17 inch (17*7J), ET is 20, and the hole spacing is 5* 120. The larger wheel hub will reduce the performance of the car, while the larger wheel rim will affect the acceleration and braking performance. With the increase of wheel rim size, its width will also increase accordingly. The bigger and wider the rim, the greater the power needed to drive it, which will affect the acceleration performance.
Wheels on the market can be divided into steel wheels and alloy wheels according to their materials, each with its own advantages and disadvantages. The main advantages of steel wheel hub are simple manufacturing process (generally casting process, for example, aluminum alloy wheel hub is generally produced by low-pressure casting process), relatively low cost and strong metal fatigue resistance, which is also commonly known as cheap and good quality. However, the disadvantages of steel hub are prominent, such as heavy weight (the same hub steel material is much heavier than aluminum alloy material), large inertia resistance and poor heat dissipation.
Alloy wheels can just make up for this problem. It has the advantages of light weight, low inertia resistance, high manufacturing accuracy, small deformation and low inertia resistance during high-speed rotation, which is beneficial to improve the straight-line driving performance of the automobile and reduce the rolling resistance of the tire, thus reducing fuel consumption.
The thermal conductivity of alloy material is about three times that of steel, which has good heat dissipation and can play a certain role in the thermal attenuation of vehicle braking system, tire and braking system. The alloy wheel hub of the original car in the market is mainly aluminum alloy. Of course, in order to meet some special requirements and improve vision, many modified wheels will choose elements such as chromium and titanium as basic materials.
However, compared with steel wheels, alloy wheels are much more expensive, so often in many low-end original cars, steel wheels will appear on low-profile models, while alloy wheels are standard on high-profile models.
(Photo/Text/Photo: Pacific Auto Network Q&A called Beast)