Compare old and new wheels to see how offset and width change inner clearance and outer poke.
Result
How to use this tool
Type its width in inches and its ET offset in mm.
Type the width and offset you are considering.
The headline result gives both changes in millimetres.
The metrics list old and new backspacing and frontspacing.
Formula & worked example
Going from ET45 to ET35 on the same 8-inch wheel moves the wheel 10 mm further out and adds 10 mm of inner clearance.
Limitations — read this before you rely on it
Geometry only. It does not check brake, suspension or arch clearance, load rating or tyre fitment for a specific vehicle.
Frequently asked questions
The distance in millimetres from the wheel centreline to the hub mounting face. Positive ET tucks the wheel inward.
The distance from the hub face to the inner edge of the rim: width/2 + offset.
Yes. Lowering ET moves the whole wheel outward, increasing poke and inner clearance by the same amount if width is unchanged.
Yes. A wider wheel grows on both sides: half the extra width goes inward and half outward, before offset is considered.
No. Clearance to suspension, brakes, arches and steering geometry all limit it. Check fitment for your vehicle before buying.