What are the parameters in the wheel hub model size chart?
4 Answers
The main parameters of automobile wheel hubs include: 1. Wheel hub size: Composed of two parameters, the rim diameter and rim width. The representation can be 15*6.5; 15*6.5JJ; 15*6.5J, etc., with no strict requirements on the format. The "15" at the front indicates the rim diameter, meaning the diameter of the wheel hub rim is 15 inches, and the "6.5" (or 6.5J, 6.5JJ) at the back indicates the rim width, representing the wheel hub rim width of 6.5 inches. 2. PCD: Refers to the pitch circle diameter of the wheel hub bolt holes. The representation is like 5*114.3, 10*100/114.3, where "5" indicates the number of bolt holes, meaning there are 5 bolt holes. "114.3" indicates that the pitch circle diameter of the bolt holes is 114.3mm. 3. Offset: This is the distance between the mounting surface and the centerline of the wheel hub, usually found on the back of the wheel hub. The offset is used to adjust the wheel track and ensure that the wheels do not interfere with the vehicle body. 4. Center bore: This is the large hole in the middle of the wheel hub. Note that the center bore size is correctly measured from the back. If the wheel hub's axle hole is large, a center bore ring must be used; otherwise, the wheel will shake at high speeds. Modified wheel hubs are generally designed with a larger center bore to fit all vehicles, while the original vehicle's center bore is usually smaller. If there is a gap, a hub-centric ring should be added.
I understand that the parameters of the wheel size chart include diameter, width, offset (ET value), bolt pattern (PCD), and center bore. The diameter is measured in inches and determines the tire size. For example, an 18-inch wheel with large tires is suitable for off-roading. The width, such as 7J, indicates the wheel width and affects tire grip. The ET value represents the wheel offset—positive ET makes the wheel concave, while negative ET makes it more prominent. Adjusting the ET value can enhance appearance but should not compromise safety. PCD is the bolt hole distribution distance and must match the vehicle's bolts. The center bore size must be precise; otherwise, a hub ring is needed during installation. I recommend checking the original vehicle manual when purchasing wheels online, as incorrect parameters may cause high-speed vibrations or braking issues. Also, consider the load-bearing capacity when modifying, but getting the main parameters right is sufficient.
When I first started learning about cars, I thought wheel size was just a single number. Later, I discovered there are multiple parameters: diameter, width, ET offset, bolt pattern (PCD), and center bore size. Diameter, such as 15 inches, is commonly used for compact cars; width like 6.5J suits narrow tires; ET value affects wheel positioning—I once got it wrong and scraped the wheel arch; bolt pattern is the circular distance between bolt holes, varying significantly across models; center bore size must match the axle—even slightly larger will cause wobbling. Don’t blindly follow trends when choosing wheel specs. I prefer using online fitment tools to input my car model for recommended values or referencing OEM data to save money and effort. Incorrect installation may increase fuel consumption or accelerate tire wear—a quick check ensures safety.
Wheel parameters such as diameter, width, offset (ET), bolt pattern (PCD), and center bore are all indispensable. Diameter affects speedometer accuracy; width influences tire pressure adjustment; positive or negative ET values alter wheel positioning, and improper offset can damage the suspension; incorrect bolt pattern makes installation difficult; oversized center bore requires spacers. I emphasize that these parameters directly impact driving safety—for example, misaligned bolt patterns pose high risks of vibration and loss of control at high speeds. When replacing wheels, it's best to bring original vehicle measurements for purchase or visit a professional shop to verify parameter compatibility—small details can lead to major hazards.
