What is backspace on a wheel?

Per the diagram, the backspace dimension is measured from the wheel's mounting face to the inner edge of the rim (toward the brake/caliper side).

Where is positive offset measured on a wheel?

The diagram shows offset (positive) as the distance between the wheel's centerline and its mounting face, with positive offset placing the mounting face toward the outside of the wheel.

What is the difference between rim width and overall rim width?

The diagram shows rim width measured inside the flanges (bead seat to bead seat), while overall rim width is measured across the full outside width of the rim including the flanges.

What is pilot diameter?

The diagram labels pilot diameter as the diameter of the center hole of the wheel that fits over the hub, shown at the center of the wheel adjacent to the bolt circle diameter.

What does static radius mean?

In the diagram, static radius is the distance from the wheel/axle centerline down to the ground with the tire mounted.

Home/ Registry/ Chevrolet/ Corvette/ 1968-1982/ “Other vette pictures”/ Photo supermotors.net/registry/media/993156

Wheel Offset & Backspacing Diagram - Rim Width, Bolt Circle & Fitment Terms

Engineering wheel and tire cross-section dimensioned with rim width, bolt circle, offset and static radius

‹ ›

Dimensioned engineering cross-section of a wheel and tire labeling section width, rim width, bolt circle, pilot diameter, offset and static radius.

AI caption August 2013 · Photo 74 of 205

This document is a technical cross-section diagram of a wheel and tire assembly mounted at a fender, used as a reference for understanding wheel fitment terminology. It labels and dimensions the key measurements involved in selecting wheels and tires: section width and tire width (measured across the tire), fender lip location, overall rim width and rim width (bead-to-bead), section height of the tire, caliper height (clearance for the brake caliper inside the wheel), a 0.920 dimension near the rim area, backspace dimension (from the mounting face to the inner rim edge), nominal wheel diameter, bolt circle diameter, pilot diameter (the center hub bore), positive offset (distance between the wheel mounting face and the rim centerline), and static radius (from the axle centerline to the ground). The centerline of the assembly is marked with a C/L symbol. A reader can learn how each of these fitment measurements is defined and where each is physically measured on a wheel, tire, hub, and brake assembly. The diagram is generic and does not state a specific vehicle make, model, or year, though it was uploaded as reference material for a 1976 Chevrolet Corvette.

Is this accurate? Sign in to help verify it.

Frequently asked questions

What is backspace on a wheel?: Per the diagram, the backspace dimension is measured from the wheel's mounting face to the inner edge of the rim (toward the brake/caliper side).
Where is positive offset measured on a wheel?: The diagram shows offset (positive) as the distance between the wheel's centerline and its mounting face, with positive offset placing the mounting face toward the outside of the wheel.
What is the difference between rim width and overall rim width?: The diagram shows rim width measured inside the flanges (bead seat to bead seat), while overall rim width is measured across the full outside width of the rim including the flanges.
What is pilot diameter?: The diagram labels pilot diameter as the diameter of the center hole of the wheel that fits over the hub, shown at the center of the wheel adjacent to the bolt circle diameter.
What does static radius mean?: In the diagram, static radius is the distance from the wheel/axle centerline down to the ground with the tire mounted.