Practical tools for measured work
Wheel Offset Calculator & Fitment Visualizer
Compare a current and proposed wheel/tyre setup and see exactly how the geometry changes.
Current setup
inches
inches
mm
section width, mm
sidewall %
Proposed setup
inches
inches
mm
section width, mm
sidewall %
How it works
Poke and backspacing are measured relative to the fixed hub mounting face. Poke = wheel width ÷ 2 − offset; backspacing = wheel width ÷ 2 + offset. A larger poke means the wheel face sits further outboard (toward the fender); a larger backspacing means the wheel barrel extends further inboard, toward suspension and brake components.
Overall tyre diameter = wheel diameter + 2 × sidewall height, where sidewall height = tyre section width × aspect ratio. Ground clearance change and speedometer error follow directly from the change in rolling radius.
Limitations
This is a geometric comparison only. It cannot know your vehicle's specific fender lip, suspension travel, steering-lock clearance, or brake caliper size - all of which also determine whether a setup physically fits. A setup that looks clear here can still rub. Always cross-check against vehicle-specific fitment data or a test fit.
FAQ
What does a positive offset change mean?
Why did my speedometer error come out positive?
Does a bigger diameter always raise the car?
Find published vehicle wheel specifications
Search by make, model or chassis, then optionally filter by model year. These are third-party reference records, not approval for a tyre or wheel change.
Verify the exact market, trim, brake package and axle against your vehicle documentation. This dataset does not supply tyre load ratings, speed ratings, pressure, clearance or an installation approval. Aftermarket flush and maximum-size suggestions are deliberately excluded.
ANKUSI Wheel Fitment Dataset (CC BY 4.0). Selected original-equipment reference fields; source data remains attributed to its publisher.
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