Auto Tools

Scrub Radius Calculator

Estimate scrub radius from wheel offset and a simplified steering-axis reference measurement.

Updated April 15, 2026
Free online tool
Planning and research use

Why this page exists

Suspension geometry gets easier to compare when offset and steering-axis reference measurements turn into one simplified scrub-radius estimate instead of being discussed only in abstract terms. This calculator helps visitors estimate scrub radius from wheel offset and a simplified geometry input.

Interactive tool

Run the estimate

Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.

Calculator

Scrub radius calculator

Estimate scrub radius from wheel offset and a simplified steering-axis reference measurement.

Result

-17.000 mm

Estimated scrub radius based on a simplified steering-axis reference measurement minus the wheel offset entered.

Estimated scrub radius-17.000 mm

Wheel offset used35.000 mm

Geometry value used18.000 mm

Summary noteNegative scrub radius

Using 18.000 mm as the simplified steering-axis reference and 35.000 mm of wheel offset gives a scrub-radius estimate near -17.000 mm.
Negative scrub radius in this simplified view means the tire-contact centerline and steering-axis ground intersection are not landing at the same point.
Measure real suspension geometry directly before making setup decisions, because this simplified method does not capture every steering-axis and tire variable.

This is a planning estimate, not a direct suspension measurement. Real scrub radius depends on full steering-axis geometry, wheel width, tire shape, ride height, and the exact points used for measurement.

Planning note

Last updated April 15, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.

How it works

What the calculator is doing

Enter wheel offset and a simplified steering-axis reference measurement using the same unit and sign convention.

The calculator subtracts wheel offset from the steering-axis reference measurement.

It shows the estimated scrub radius, the measurements used, and a simple positive-or-negative note.

Understanding your result

This is a planning estimate only. Real scrub radius depends on full suspension geometry, wheel and tire setup, and direct measurement on the actual vehicle.

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Examples

Ways people use this tool

Example scenarios help turn a quick estimate into a more useful comparison or planning step.

Compare two wheel-offset choices

Changing the offset input can show how much a wheel change could move the simplified scrub-radius estimate.

Check a before-and-after setup idea

This is useful when you want a quick estimate before measuring a real suspension directly.

Use it with wheel-fitment tools

Scrub-radius planning often fits naturally beside wheel offset, spacer, and backspacing tools.

FAQ

Common questions

How is scrub radius estimated here?

The calculator uses a simplified geometry method that subtracts wheel offset from the steering-axis reference measurement entered in the same sign convention.

Why is this only a planning estimate?

Real scrub radius depends on the full steering-axis geometry and the actual wheel-and-tire setup, not just two simplified measurements.

What does a positive or negative result mean?

It shows which side of the simplified steering-axis reference the tire-contact centerline lands on in this basic geometry view.

Related tools

Keep comparing

Use these related tools to compare nearby scenarios, check a second estimate, or keep narrowing down the right decision.

Auto ToolsUpdated April 11, 2026