What materials are used for wheels: iron, aluminum, magnesium. Teflon coatings are sometimes also applied for an extra layer of protection.
What is the wheel diameter: distance between the bead seats (for the tire), as measured in the plane of the rim and through the axis of the hub which is or will be attached, or which is integral with the rim. Unit of measure for wheel diameter is inch.
What is the wheel width: a separation distance between opposed wheel flanges. The flange-to-flange width should be a minimum of three-quarters of the tire section width and the maximum rim width should be equal to the width of the tire tread. Unit of measure for wheel diameter is inch.
What is the wheel hub: the hub is the center part of the wheel with the bolts used to secure to the hub assembly where are located brake pads, calipers, and rotors. On car wheels can be 3,4,5,6 or 8 bolts depends on the weight and speed of the car. Unit of measure for wheel hub is mm.
What is the wheel offset: wheel offset is the distance from the hub assembly where the wheel is mounted to the wheel's center. The centerline is the literal “center” of the width of your wheel. This centerline is also known as a 0 mm offset. Unit of measure for wheel hub is mm.
What is the wheel ET: wheel ET is the offset
Offset can be negative, zero or positive so decreasing offset means wheel moving towards the outer.
What is the wheel bolt pattern: the bolt pattern or lug pattern is the diameter of an imaginary circle formed by the centers of the wheel lugs. Bolt patterns may contain 4-, 5-, 6-, or 8-lug holes. Bolt pattern is showed as number of bolt/lug and diameter in mm or inch of the circle formed by the center of wheel lug. So 6x120 means 6 bolts with 120 mm circle diameter. There are several bolt pattern depends on the car weight, speed and car brands that on same type, weight and speed can use different bolt pattern.
Source:
https://en.wikipedia.org/wiki/Rim_(wheel)
https://rnrtires.com/tips-guides/the-basic-parts-of-a-car-wheel-and-tire/
https://jr-wheels.com/et-calculator
https://www.wheel-size.com/pcd/
https://measuringstuff.com/38-cars-that-have-a-5x120-bolt-pattern/
edited by arrabbiata
