Automotive
Tire size comparison
Compare nominal tire diameter and the geometric change in speedometer reading.
Calculators / Automotive / Wheel offset and clearance change
Wheel offset and clearance change calculator
Compare nominal wheel positions using width and offset.
On this page
Extra outward extension22.7mm
Loss of inner clearance2.7mm
Calculator controls
How to calculate
Compare nominal wheel positions using width and offset.
Outward change = half width change + old offset − new offset; inner clearance loss = half width change + new offset − old offset.
Worked example
Original wheel width (inches): 7; Original offset ET (mm): 45; New wheel width (inches): 8; New offset ET (mm): 35.
Extra outward extension: 22.7 mm; Loss of inner clearance: 2.7 mm.
Assumptions and limits
Compare nominal wheel positions using width and offset. Negative inner-clearance loss means more clearance. Tire sidewalls, flanges, brake clearance, suspension movement and load ratings are not modeled; check fitment physically.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Compare nominal wheel positions using width and offset. Negative inner-clearance loss means more clearance. Tire sidewalls, flanges, brake clearance, suspension movement and load ratings are not modeled; check fitment physically.
When this tool is useful
Outward change = half width change + old offset − new offset; inner clearance loss = half width change + new offset − old offset.
Understanding your inputs
| Input | What to enter |
|---|---|
| Original wheel width (inches) | Enter a number of at least 1 and no more than 30. |
| Original offset ET (mm) | Enter a number of at least -200 and no more than 200. |
| New wheel width (inches) | Enter a number of at least 1 and no more than 30. |
| New offset ET (mm) | Enter a number of at least -200 and no more than 200. |
Frequently asked questions
Does a smaller offset always mean more inner clearance?
The wheel centre moves outward as offset decreases, but width changes also affect the inner edge. Compare both width and offset, then verify brakes, tires and suspension on the vehicle.