Wheel Backspacing Calculator

Wheel backspacing and offset are two ways of measuring how far a wheel sits inward or outward from the hub — and the Wheel Backspacing Calculator converts between them using your wheel width. Enter your wheel width, then select whether you're starting from a known offset (mm) or a known backspace (inches) to get the converted value. Secondary outputs include frontspace — the gap between the hub face and the outer lip of the wheel.

inches

Measured between tire bead seats

Calculate From *

mm
inches

Results

Calculated Backspace

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Calculated Offset

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Frontspace

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Frequently Asked Questions

What is wheel backspacing?

Wheel backspacing is the distance from the wheel's mounting surface to the inner edge of the wheel. It determines how far the wheel sits inward toward the vehicle's suspension components.

What is wheel offset?

Wheel offset is the distance from the wheel's centerline to the mounting surface. Positive offset means the mounting surface is toward the front of the wheel, while negative offset means it's toward the back.

How do I convert backspace to offset?

Use the formula: Offset (mm) = 25.4 × [Backspace (inches) - (Wheel Width + 1) ÷ 2]. This calculator does the conversion automatically when you enter your measurements.

What's the difference between backspace and frontspace?

Backspace is measured from the mounting surface to the inner wheel edge, while frontspace is from the mounting surface to the outer wheel edge. Together they equal the total wheel width plus rim lips.

Why is proper wheel backspacing important?

Correct backspacing ensures proper clearance from suspension components, brake calipers, and fender wells. Incorrect backspacing can cause rubbing, handling issues, or bearing stress.

Can I use any wheel width with any backspacing?

No, backspacing must be compatible with your vehicle's specifications. Wider wheels typically require different backspacing to maintain proper clearances and track width.

What happens if my backspacing is wrong?

Incorrect backspacing can cause tire rubbing on suspension components or fender wells, altered scrub radius affecting handling, and increased stress on wheel bearings and suspension parts.