Wheel Offset Calculator
Compare your current wheels to a new set. See how far the outer edge moves toward the fender (poke) and the inner edge toward the suspension, in millimeters and inches. Updates as you type.
Current wheel
New wheel
How to read the result
- Poke is how much further the outer lip sits toward the fender. Positive means the new wheel sticks out more; negative means it tucks in.
- Inner edge is the suspension side. A positive number means the wheel moves closer to the strut, control arm or brake — the usual source of rubbing.
- Centerline shift is the offset difference alone. Lowering offset by 26 mm moves the whole wheel out 26 mm before width is considered.
- Backspacing is the distance from the mounting face to the
inner lip — the number lift and off-road shops quote. Formula:
width / 2 + 0.5 + offset ÷ 25.4.
What wheel offset means
Offset (often stamped ET, from the German Einpresstiefe) is the distance in millimeters between the wheel's mounting face and its centerline. Positive offset puts the mounting face toward the street side, so the wheel tucks inward. Negative offset pushes the wheel outward — the "deep dish" look on lifted trucks. Zero offset centers the mounting face.
Offset alone does not tell you where the edges are. A wider wheel at the same offset grows equally in both directions, so a 9-inch wheel at +18 sits very differently from a 7.5-inch at +18. That is why this tool compares both wheels.
Common gotchas
- Going from +44 to +18 on a wider wheel is a common truck upgrade and usually means 45 mm more poke — often more than a stock fender covers.
- Rubbing on the inside is the one people miss. Check the inner-edge number, not just poke.
- Wheel spacers add negative offset: a 25 mm spacer is the same as lowering offset by 25 mm.
- Tire width changes clearance too. This tool is wheel-only; a wider tire adds roughly half its extra width to each side.