Wheel Cross-Section Diagram - Offset, Back Spacing, Rim Width Terminology

This document is a labeled cross-section diagram of an automotive wheel, illustrating standard wheel measurement terminology. The diagram shows a wheel in profile (cut-away) view with dimension lines and callouts identifying key measurements and features: Rim Width, Bead Seat, Drop Center, Hump, Back Spacing, Wheel Diameter, Mounting Surface Diameter, Hub Hole Diameter, Pitch Center Diameter, the Wheel Mounting Surface, X Factor, Offset, Front Flange, and Center Line. It also labels the two sides of the wheel as the 'Drum Side' (inboard, brake side) and 'Street Side' (outboard, visible side). The diagram demonstrates how offset is measured relative to the wheel's center line and mounting surface, and how back spacing is measured from the mounting surface to the inner rim edge. The image is watermarked 'Buicks.net,' indicating its source. This reference is useful for anyone measuring wheels for fitment—determining whether a wheel will clear brakes and suspension components—since it visually defines the relationship between rim width, back spacing, offset, and the mounting surface. No specific vehicle year, make, model, part numbers, or numeric dimensions are given; it is a generic terminology/measurement reference diagram.