Wheel Offset Comparison
Deciding between a few wheels? Enter your current wheel and up to three candidates for a side-by-side wheel offset comparison. Each column shows how far that wheel's edges move relative to what you have now.
Current wheel
Candidates
| Wheel A | Wheel B | Wheel C | |
|---|---|---|---|
| Width (in) | |||
| Offset (mm) | |||
| Outer edge (poke) | |||
| Inner edge | |||
| Backspacing |
How to read the table
- Outer edge: positive = pokes out further than your current wheel; negative = tucks in.
- Inner edge: positive = closer to the strut / control arm; negative = more inner clearance.
- A wider wheel at the same offset moves both edges out by half the width increase. Lower offset moves the whole wheel out.
Worked example: 7.5" ET44 compared with three wider wheels
These are the default values above. The current wheel is 7.5 inches wide with a +44 mm offset; the three candidates get wider and lower in offset.
| Wheel | Outer edge | Inner edge | Backspacing |
|---|---|---|---|
| Current 7.5" ET44 | 0 | 0 | 5.98" |
| A: 8.5" ET30 | +26.7 mm out | −1.3 mm (away) | 5.93" |
| B: 9" ET18 | +45.05 mm out | −6.95 mm (away) | 5.71" |
| C: 9" ET0 | +63.05 mm out | −24.95 mm (away) | 5.00" |
Wheel A is one inch (25.4 mm) wider, so each edge moves 12.7 mm before offset counts. Its offset is 14 mm lower, which shifts the whole wheel 14 mm outward: the outer edge moves 12.7 + 14 = 26.7 mm out, the inner edge 12.7 − 14 = −1.3 mm, so it sits slightly further from the strut than the stock wheel. Every candidate here trades inner clearance for poke; whether 26.7 mm or 63 mm of poke fits depends on your fender, which the fit check measures against.
Offset comparison formulas: poke, inner clearance, backspacing
- Outer edge change (mm) = (new width − old width) × 25.4 ÷ 2 + (old offset − new offset)
- Inner edge change (mm) = (new width − old width) × 25.4 ÷ 2 − (old offset − new offset)
- Backspacing (in) = width ÷ 2 + offset ÷ 25.4 + 0.5, because the overall wheel is about one inch wider than its nominal rim width. The backspacing calculator converts in both directions.
Comparing wheels: common questions
How do I compare three wheels at once?
Enter your current wheel once, then up to three candidates. Each row reports poke, inner clearance and backspacing against the same baseline, so the numbers are directly comparable; comparing them one at a time in separate tools is what makes two candidates look similar when they are not.
Two wheels are the same width but different offset. How much does that matter?
Millimetre for millimetre on both edges. A 9-inch wheel at ET18 pokes 45.0 mm more than a stock 7.5-inch ET44, while the same 9-inch wheel at ET35 pokes 28.0 mm. Same wheel, 17 mm of offset, and 17.0 mm of difference at the fender.
Which number should decide it, poke or inner clearance?
Inner clearance, almost always. Poke is visible and is usually the reason for the change, but the strut, control arm and brake caliper are what the wheel actually hits, and that edge moves the opposite way. A candidate that wins on stance and loses on inner clearance is the wrong wheel.
Does this account for tire width?
No, this page compares wheels only. A wider tire adds roughly half its extra width to each side on top of these figures; use the full fitment check when the tire size changes too.