Compare current and new wheel width, diameter, and offset to see how the wheel moves inward and outward. This tool does not evaluate vehicle-specific clearance. Wheel offset explained
15 mm lower offset
Mounting position shifts outward
2.3 mm more inner clearance
More room toward the suspension
27.7 mm farther outward
Extends farther toward the fender
55.4 mm wider across the axle
Estimated when fitted on both sides
0.09 in less backspacing
New backspacing: 5.29 in
The new wheel sits 27.7 mm farther outward and provides 2.3 mm more inner clearance. This creates a wider stance. Confirm your vehicle’s actual fender and suspension clearances before purchasing.
Confirm these clearances on your specific vehicle before purchasing.
Tire size, ride height, camber and bodywork may affect final fitment.
See how the new wheel moves relative to your current wheel. Actual vehicle clearance is not measured.
Positive offset moves the mounting face toward the wheel’s outer face; negative offset moves it toward the suspension side.
Left diagram is the current wheel; right is the new wheel. Suspension side is inward; fender side is outward.
Results describe relative wheel position only. Measure actual clearances on your vehicle before purchasing wheels or tires.
Wheel width and offset must be evaluated together. An offset change of 0 mm can still create a major position change when the new wheel is wider.
The mounting face sits farther toward the outside face of the wheel and usually moves the wheel inward relative to a wheel of the same width.
The mounting face aligns with the wheel centerline. Backspacing equals half the nominal wheel width.
The mounting face sits toward the suspension side of the centerline and usually moves the wheel outward relative to a wheel of the same width.
5.38in
Formula: Backspacing = (Width / 2) + (Offset ÷ 25.4)
Calculated backspacing uses the wheel’s nominal width. Manufacturer measurements may differ slightly because the physical rim flanges extend beyond the stated wheel width.
Offset (ET, from the German Einpresstiefe) is the signed distance in millimeters from the wheel centerline to the hub mounting pad. Positive ET places the pad toward the outer face of the wheel; negative ET places it toward the suspension side; zero ET puts the pad on the centerline.
Offset alone does not locate the lips. Nominal wheel width sets how far each lip sits from the centerline, so the same ET on two different widths produces different inner and outer positions relative to the hub.
Because inner and outer lip positions are functions of both width and offset. On a fixed offset, increasing width moves both lips outward from the centerline by half the width increase (in the same units).
This calculator therefore reports inner-position change, outer-position change, and estimated track-width change from the full current vs new setup—not from the offset delta alone. Treat a “same offset” swap onto a wider wheel as a geometry change that still needs clearance review.
Outer position is modeled as the hub-face-to-outer-lip distance from nominal width and offset. The per-wheel outer change is new outer position minus current outer position. Estimated track-width change is twice that value, which assumes the same wheel setup is fitted on both sides of the axle.
These are relative geometry deltas for the wheel assembly as specified. They are not measured tire-to-fender gaps, and they do not include tire section width, sidewall bulge, or suspension deflection.
Using nominal wheel width W (inches) and offset ET (mm): backspacing ≈ W/2 + ET/25.4 (inches from the hub pad to the inner rim lip). Solving for offset: ET ≈ (backspacing − W/2) × 25.4.
Wider wheels increase backspacing at the same ET because half-width grows. Catalog “backspace” figures can also differ slightly from this nominal conversion when manufacturers measure to a different flange reference, so treat the on-page converter as a nominal engineering translation—not a substitute for the wheel maker’s published datasheet.
Clearance is a vehicle-state problem. Hub face location, strut and lower-control-arm packaging, brake caliper envelope, steering lock geometry, fender and liner shape, tire section and construction, load, inflation, camber, toe, and ride height all change the free space around the wheel.
This calculator compares relative wheel position between two specs and explicitly does not evaluate vehicle-specific clearance. Use the reported inner and outer deltas to decide where to measure, then verify on the vehicle at ride height and full lock.
Offset difference is a weak proxy when width also changes. Prefer the largest absolute lip movement (inner or outer) and the estimated track-width change. Minimal or small shifts are usually easier to package; moderate changes deserve targeted checks; large or very large changes justify measuring suspension/strut, brake/caliper, tire-to-fender, and steering-lock clearances before purchase.
Magnitude labels describe relative geometry severity only. They are not fitment pass/fail verdicts and do not guarantee that a given vehicle will clear.
