Wheel size, Offset, PCD, Clearance, Tyre Size, Explained with illustrations

Name of Wheel Parts
Name of wheel parts

Wheel Size
Wheel size

The offset indicates the distance from the center of the rim to the attaching disk part (unit:m/m). As seen in the attached drawing, the offset is indicated by "+" when the fitting surface extends beyond the central line of the rim and "-" when it is falls within. Caution is required to prevent the tire from coming into contact with the fender of the vehicle or the brake caliper if the offsets are very different.

The number of bolts used to install a wheel varies from 4 to 6 depending on the vehicle model (except for some vehicle type), thus the wheel to be installed should also possess the same number of hub bolt holes. P.C.D. stands for pitch circle diameter, and indicates the diameter of the circle in mm connecting the center of each hub bolt. Since the P.C.D. also varies according to the vehicle model, make sure a suitable one is selected.

Fender clearance indicates the marginal space between the tire and the fender or body of the vehicle. Inner clearance indicates the distance between the tire and wheel and the body part which is positioned closest to the tire and wheel. Dimensions for both right and left clearance should be measured on a level surface, and the smaller value is then considered as the inner clearance.

Tyre Size
Tyre Size
1-Tire width (mm or inch)
2-Aspect ratio
3-Radial construction
4-Rim diameter
5-Load index
6-Speed symbol
7-Tire outer diameter (inch)
8-Ply rating

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Updated 14 Mar 2008