[Things to know about changing rims] Guide to choosing rims | 6 essential numbers to know | Which is better, casting, forging, or spinning?

Wheel rims (tires) are an essential component of every car. In addition to bearing tire. In addition, it also directly affects the driving control, safety and overall appearance. Many car owners, whether buying a new car or a used car, will choose to replace the rims. Most of the reasons are for appearance. But when replacing the rims, what should you pay attention to? Kwiksure share the main materials, sizes and specifications of rims, as well as the key points to pay attention to when changing rims.

Why change rims?

There are many reasons to replace rims, but most often it's to improve driving performance or aesthetics. For example, lightweight rims can effectively reduce a vehicle's load, allowing the suspension system to better absorb road vibrations while also improving grip, resulting in more stable cornering and significantly enhanced driving safety. Furthermore, high-quality rims help evenly distribute tire pressure, increasing stability over uneven surfaces, reducing uneven tire wear, and lowering the risk of blowouts. Of course, another important factor is that lightweight rims reduce vehicle weight, which helps improve fuel efficiency.

3 main rim materials

Currently, the most common wheel rim materials on the market are steel, aluminum alloy and carbon fiber.

Steel rims:Commonly known as alloy bells, they are low-cost and durable, and are mostly used in entry-level models or commercial vehicles. Their disadvantages include being heavy, having average handling performance, and a rather dull appearance.

Aluminum alloy wheels:Currently the most popular choice, aluminum alloy wheels combine lightweight and strength to effectively improve handling and fuel efficiency. Furthermore, aluminum alloy wheels can be manufactured in a variety of ways, including casting, forging, and spinning. Forged wheels are particularly popular among performance car enthusiasts due to their high strength and light weight, making them suitable for intense driving and racing.

Carbon fiber rims:A high-end choice, boasting exceptional lightness and strength, but due to its high price, it's more commonly found in supercars and top-tier modified vehicles. Carbon fiber not only reduces vehicle weight but also offers excellent corrosion resistance, helping to enhance vehicle dynamics. However, it's rarely used in everyday vehicles.

Is casting, forging or spinning better?

Casting wheel rims are made by melting aluminum at high temperature and then pouring it into a mold to cool it down. The material density is low and the strength is relatively weak., but the manufacturing process is simple and the cost is low, so they are often used on basic or entry-level vehicles. Cast wheels are heavier, have a high degree of design freedom, a variety of appearances, and are more affordable.

Forging wheels are made by extruding heated and softened aluminum ingots with a high-pressure hydraulic press, which greatly increases the density and strength of the material., with a tight structure and no potential for air bubbles in casting. Forged wheels offer high strength, light weight, excellent toughness, and impact resistance, resulting in superior performance but high cost. They are typically used on high-performance vehicles. Forged wheels are often CNC-machined, resulting in a limited number of designs.

Flow Forming, also known as spinning casting, is to first cast the wheel rim embryo, and then use the rotational pressure to stretch and thin the wheel rim part, which is similar to the concept of hand-thrown billets.The strength of spun rims is between casting and forging, and is lighter and stronger than casting.The cost is lower than forging, but the shape is more monotonous. This process combines the diversity of the disc surface of casting with the strength and lightness of spinning, making it a cost-effective choice.

6 must-know numbers for changing rims

When choosing wheels, it's crucial to understand their size and specifications. Rim size primarily consists of diameter and width. Diameter is often measured in inches, such as 18 inches and 19 inches. Larger diameter rims are often paired with lower-profile tires, which improves driving stability and handling, but reduces comfort. Width determines the tire compatibility range; mismatched widths can affect grip and driving safety.

Besides size, the number of screw holes and the pitch circle diameter (PCD) are key parameters for securing the rim to the vehicle. For example, a five-hole, 114.3mm pitch is a common specification. This means the rim has five screw holes, with the two furthest holes 114.3mm apart. The hole spacing must align with the axle for secure installation. Offset, the distance between the rim's mounting surface and the rim's centerline, influences the rim's position within the wheel arch and the tire-to-body clearance during driving. A positive offset value generally brings the rim closer to the center of the vehicle, while a negative offset causes the rim to protrude beyond the vehicle.

In addition, the center hole diameter must also match the wheel axle center to ensure a stable installation and avoid wobble. This information is usually marked on the back or side of the rim, or can be found in the vehicle manual.

Precautions for changing rims

Before replacing rims, carefully confirm that the rim dimensions, hole spacing, and offset are fully compatible with your vehicle's requirements to avoid installation difficulties or safety hazards. Dimensional deviations can cause inaccurate speedometers and even affect the function of the wheel speed sensors.

The wheel material and weight should also be determined based on the intended use. For example, for everyday commuting, cast aluminum alloy wheels can be chosen for their cost-effectiveness, while performance car owners can consider forged or carbon fiber wheels for improved handling and acceleration.

Additionally, be sure to identify the brand and quality certifications to ensure the durability and safety of the rims. Low-quality rims are prone to cracking or deformation, which can compromise driving safety. Regularly inspect the rims after installation to avoid potential damage from prolonged use. Consult a professional wheel/tire modification shop or technician for advice, and choose the right rim based on your driving needs (e.g., handling, comfort, aesthetics, or off-road capability).

Finally, after replacing the rims, it is recommended to perform a four-wheel alignment to maintain driving stability and handling accuracy.

Choosing the right wheel and tire combination

The rim diameter must match the tire inner diameter: For example, 17-inch wheels must be matched with tires marked "xx/xxR17".

Rim width (J value) and tire width matchingEach J value has a corresponding ideal tire width range. For example, an 8J rim should be paired with a 225-245mm wide tire. Choosing a tire that is too narrow or too wide will affect grip and safety.

Maintains total diameter close to factory settingWhen upgrading to larger-diameter rims, choose tires with a lower profile (thinner sidewalls) to maintain the overall outer diameter. It's not recommended to vary the overall diameter by more than ±1% to 1.5% from the factory setting to ensure speedometer accuracy and proper functioning of the suspension and shock absorbers.

Pay attention to the number of screw holes and PCD of the rim, which must meet the specifications.: The basis for ensuring the safe installation of the rim.

Frequently Asked Questions

When changing rims, how can I ensure the size matches my vehicle?

It is necessary to confirm that the rim diameter, width, number of screw holes, hole spacing (PCD), offset, and center hole diameter fully meet the vehicle requirements to avoid installation difficulties or affect driving safety.

What are the differences between casting, forging and spinning of aluminum alloy wheels?

Casting has low cost but is heavier, making it suitable for daily use; forging has high strength and is light, making it the first choice for performance cars; spinning is somewhere in between, combining lightness and cost-effectiveness, making it a balanced choice.