FitmentPro

Wheel Offset Calculator (Flush & Poke)

Enter the diameter, rim width and offset of your current and planned wheels to see how far they move out and in, and whether they poke or rub.

These calculations are theoretical.Details
[Disclaimer] These calculations are theoretical. Actual fitment may vary due to vehicle manufacturing tolerances, suspension geometry, and actual tire dimensions, which vary by brand. Always test fit before driving.

Current SetupBefore

New SetupAfter

INNER CLEARANCEMeasured

Distance from original inner wheel/tire to suspension (mm)

OUTER CLEARANCEMeasured

Distance from original outer wheel/tire to fender (mm)
Suspension / StrutHub Mounting Surface
Current Setup
New Setup
✓

Inner clearance left: 15.00 mm

Inner clearance OK

!

⚠ Will interfere with or poke out past fender

Outer interference risk

Position change

Outer+25.0mm
Inner+5.0mm

Speedometer Error

-3.44%
Actual speed at an indicated 100 km/h
96.6km/h
* Error exceeds ±3%. May fail vehicle inspection depending on local laws.
Diameter (mm)659.9637.2
Circumference2073.12001.8
Outer change (poke)
Outer +25.0mm / Inner +5.0mm

What to check before fitting

Inset and how far the wheel sits out
Inset (offset) is how many millimetres the mounting face sits outboard of the centreline of the rim. The smaller the number, and the further into negative it goes, the further out the wheel sits. The outer face moves by roughly the same amount as the change in inset: take 10 mm off the inset and the wheel moves about 10 mm outboard. If you change rim width too, half of the extra width is added on each side.
The rule on poke
Since the Japanese regulation was amended on 22 June 2017, where the outermost part is the tyre itself, a protrusion of less than 10 mm is permitted within 30 degrees forward and 50 degrees rearward of the wheel centre. This applies only to passenger cars; commercial vehicles on 1- and 4-series plates are not covered even for the tyre. Protrusion of the wheel rim itself is outside this allowance and is never permitted.
Inboard clearance
Deciding on the outer face alone is how you end up rubbing on the inside. Increasing inset pulls the wheel inboard and cuts the gap to the strut, suspension arms, brake caliper and tie rod. Check at full lock in both directions and with the suspension at full bump.
Rim width versus real tyre width
The actual section width of a tyre depends on the rim it is mounted on. As a rule of thumb, half an inch more rim width gives roughly 5 mm more tyre width. The width in the size marking is the value at the reference rim, so allow for this when you change rim width.
PCD, bolt count, centre bore and torque
Even with the outer face right, the wheel will not fit unless PCD (the diameter of the circle through the bolt holes) and the number of holes match. If the centre bore is smaller than the vehicle hub it will not go on; if larger, use hub rings to centre it. After fitting, torque the wheel nuts to the specified figure and re-check them after driving.

FAQ / FAQ

What is wheel offset (ET)?

Offset is the distance in mm from the hub mounting face to the rim centerline. A lower or negative ET pushes the wheel outward (more poke), while a higher ET tucks it further inside the fender.

How far does the wheel move if offset changes by 10 mm?

Dropping the offset by 10 mm moves the whole wheel 10 mm outward. Going 1 inch wider on the rim also adds about 12.7 mm per side. Add both effects together to get the final poke or tuck.

How do I calculate a flush fitment?

Measure the gap from the outer edge of your current wheel to the fender, then enter the new rim width and offset here and check the "Outer" change. Keep it slightly below the measured gap — leave 3–5 mm of margin.

What do wheel spacers do? Will they pass inspection?

A spacer pushes the wheel outward by its thickness, exactly like lowering the offset. Wheels poking past the fender may fail inspection in many regions, and you must keep enough stud or bolt engagement.

Related tools

Tire Diameter Calculator (TireDiff)

Calculate tire diameter, circumference and speedometer error, and compare two sizes.

Wheel Nut Torque Guide (TorqueSpec)

Reference tightening torque by manufacturer, thread specs, seat types and unit conversion.

Coilover Setup Calculator (CoiloverPro)

Visualize ride-height change, rake, and stroke split for full-tap coilovers.

Japan Car Tax & Inspection Cost (TaxCalc)

Estimate Japanese vehicle taxes and statutory shaken fees (Japanese only).

Wheel Search (WheelFinder)

Find matching wheels by diameter, rim width, PCD, bolt count and offset.

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Calculation results on this site are theoretical estimates based on your inputs; their accuracy, completeness, and safety are not guaranteed. The site operator assumes no liability for any damages arising from the use of this site.