See how changing rim width or offset moves the outer and inner lips: poke toward the fender or tuck toward the suspension, in inches and mm — free, private.
+0.89"
Outer lip (poke)
+22.7 mm
+0.11"
Inner lip (tuck)
+2.7 mm
+1"
Width change
-10 mm
Offset change
Watch outer clearance
Outer lip moves outward by ~0.25" or more. Check fender and lip clearance carefully.
Positive outer = more poke toward the fender. Positive inner = deeper toward the suspension. Estimates ignore fender roll and tire bulge.
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Enter current and new rim width plus current and new offset. The calculator shows how far the outer lip moves toward the fender (poke) and the inner lip toward the suspension (tuck), in inches and millimetres. That is the geometry of a 9" ET35 replacing an 8" ET45 — not a marketing “aggressive stance” label.
Hints mark ok, watch the outer, watch the inner, or watch both when poke or tuck approaches about 0.25". That is a caution to mock-up or measure, not a guarantee of rub. Fender rolls, lift, and tire bulge still sit outside the number.
A wider wheel adds half the extra width to each side; a lower (more negative) offset adds poke. The formulas are outer = Δwidth/2 − ΔET/25.4 and inner = Δwidth/2 + ΔET/25.4, with ET in millimetres and width in inches. Seeing both deltas stops you from blaming only ET for a width change.
No vehicle upload and no account. This compares two wheel geometries, not your measured fender arch. For OE ET and bolt pattern, use Vehicle Fit; for ET ↔ backspacing, use the converter. Close the tab and the numbers are gone.
Use the wheels you have now (or OE). Width in inches, ET in millimetres, including negative offset.
Catalog figures for the wheel you want. A width change with the same ET still moves both lips.
Positive outer is more poke toward the fender; positive inner is more inward toward control arms and brakes.
Measure studs, calipers, and fender lip on the car. Spacers are a different tool; they add poke without changing the wheel’s ET stamp.
Straight answers on privacy, limits, and how the workspace behaves.
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