When it comes to wheels, the termssize,PCD,ET, andCB refer to important specifications that ensure proper fitment and performance on a vehicle. Here's a breakdown of each term:
The size of a wheel typically refers to two key measurements:diameter andwidth.
Diameter: The overall diameter of the wheel, usually measured in inches. Common sizes include 15-inch, 16-inch, 17-inch, 18-inch, and so on. This measurement corresponds to the distance from one end of the wheel to the other, from edge to edge.
Width: The width of the wheel is also measured in inches and refers to the distance between the inside edges of the wheel's rim, where the tire sits. For example, you might see a wheel labeled as 18x8.5, which means the wheel has an 18-inch diameter and an 8.5-inch width.
Example: A wheel size of18x8.5 means:
· 18 inches in diameter
· 8.5 inches in width
· Definition: PCD refers to thediameter of the circle formed by the centers of the wheel’s bolt holes.
· Format: It's represented by two numbers: the number of bolt holes (studs) and the diameter of the circle (in mm). For example,5x114.3 means:
o 5 bolt holes
o 114.3 mm diameter of the circle passing through the center of the bolt holes.
Example:5x114.3 means:
· 5 bolt holes
· A bolt circle diameter of 114.3 mm
· Definition: ET, oroffset, is the distance from the wheel’s mounting face (the part that contacts the hub) to the wheel’s centerline.
· Types:
o Positive Offset (ET +): The mounting face is towards the front (towards the wheel's outer side), pushing the wheel inward.
o Negative Offset (ET -): The mounting face is towards the back, pushing the wheel outward.
o Zero Offset (ET 0): The mounting face is aligned with the centerline of the wheel.
Example:ET40 means:
· The mounting face is 40 mm towards the outside of the wheel centerline.
Definition: Thecenter bore is the diameter of the hole in the middle of the wheel, which fits over the hub of the vehicle. It’s crucial for the wheel to match the hub size to ensure the wheel is properly centered.
Common Sizes: Center bore sizes vary based on the vehicle make and model. For instance, common center bore sizes are56.1 mm,66.1 mm, or70.3 mm.
Example:CB 66.1 means:
· The center bore is 66.1 mm in diameter.
