Wheel types
All wheels are not made the same. The performance of an alloy wheel is a direct result of the manufacturing technique employed. Some countries though, like Germany and Japan, have government regulations requiring aftermarket wheels to meet certain criteria and ensure proper fit.
There is a good variety of ways of constructing wheels. Most alloy wheels are made in either one, two or three piece construction types
One-Piece Cast Wheels
This is the most common type of aluminum wheel. The casting of wheels is the process of getting molten aluminum inside a mold to form a wheel. There are different ways this can be accomplished and although it sounds simple, this is truly an art when done properly. Gravity casting, low pressure casting and spun-rim are some of the processes to do casting wheels.
Forged
The ultimate in one-piece wheels. Forging is the process of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure. This creates a finished product that is very dense, very strong and therefore can be very light. The costs of tooling, development, equipment, etc., make this type of wheel very exclusive and usually demand a high price in the aftermarket.
Multi-Piece Wheels
This type of wheel utilizes two or three components assembled together to produce a finished wheel. Multi-piece wheels can use many different methods of manufacturing. Centers can be cast in various methods or forged. The rim sections for 3-piece wheels are normally spun from disks of aluminum. Generally, spun rim sections offer the ability to custom-tailor wheels for special applications that would not be available otherwise. The rim sections are bolted to the center and normally a sealant is applied in or on the assembly area to seal the wheel. This type of 3-piece construction was originally developed for racing in the early 1970s and has been used on cars ever since. The 3-piece wheels are most popular in the 17" and larger diameters.
There are now many options for 2-piece wheels in the market. The 2-piece wheel design does not offer as wide a range of application that a 3-piece wheel allows, however they are more common in the market and the prices start well below the average 3-piece wheel. Some 2-piece wheels have the center bolted into a cast or cast/spun rim section and other manufacturers press centers into spun rim sections and weld the unit together. When BBS developed a new 2-piece wheel to replace the previous 3-piece street wheel, they used the special rim-rolling technology (originally developed for racing wheels) to give the rim section the weight and strength advantages similar to a forged rim.
Wheel Accessories
The hubcap
The hubcap has an aesthetical function as it complete and enrich the style of the wheel and apractical function as it hides the center hole of the wheel while leaving in view the fixing holes. The hubcap varies according to the design, finish and PCD of the wheel.
The center cap
The center cap is used to cover both the center hole of the wheel and the fixing holes. It serves to complete and enrich the style of the wheel. The center cap depends exclusively on the design of the wheel.
How to Choose a Quality Wheel
1. Ask for the TÜV certificate that guarantees compliance with the minimum structural parameters (rotating flexion, impact, rolling). Failing the TÜV certification, structural solidity is uncertain: it might be possible that the product would “dramatically” break down during its use.
2. Check that the product mounted on your car does not evidence clear centring and balancing problems. If these parameters are not complied with, material damage to the car’s mechanics might ensue in the medium/long term.
3. Ask the supplier which painting tests the product passed before being released for sale. In this respect, OZ complies with the parameters required by the biggest car manufacturers.
4. Ask if the product is covered by any kind of insurance guarantee.
5. Check that the product is accompanies, on the back, by all the relevant information to allow it to be traced to the correct manufacturer and production date. Remember that the first person responsible for the sale is always the retailer.
6. If you are offered light products, always ask for maximum load resistance.
7. When you take price into account, remember that the wheel can have various degrees of strength: spending a bit more might mean investing in a long-lasting product and, above all, in a guarantee of safety.
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