Comparison
225/45 R18 vs 235/55 R17
Switching from 225/45 R18 to 235/55 R17 steps down to a 17-inch wheel — a familiar move for winter and dedicated all-terrain sets. This swap moves rolling diameter well outside the usual OEM tolerance. Extra sidewall absorbs impacts more readily — a sensible bias for daily commuting and broken pavement.
Indicated speed will drift far enough that recalibration is worth considering. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 235/55 R17 is 30.6 mm taller than 225/45 R18, shifting the speedometer by +4.64%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+30.6 mm
4.64%
Speedometer at 100
104.6 km/h
+4.64% error
Ground clearance
+15.3 mm
ride height delta
Sidewall change
+28.0 mm
revs/km: 461.1
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/compare/225-45-r18-vs-235-55-r17Detailed comparison
| Metric | 225/45 R18 | 235/55 R17 | Difference |
|---|---|---|---|
| Overall diameter | 659.7 mm | 690.3 mm | +30.6 mm (+4.64%) |
| Sidewall height | 101.3 mm | 129.3 mm | +28.0 mm |
| Circumference | 2.073 m | 2.169 m | +96.1 mm |
| Revs / km | 482.5 | 461.1 | -21.4 |
| Ground clearance | reference | +15.3 mm | +15.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.6 km/h | +4.64 km/h |
Verdict: warning
Between 3% and 5% — noticeable speedometer drift; recalibration may be advisable.
Speedometer impact
At a true 100 km/h, your dashboard will read 104.6 km/h after switching to 235/55 R17 — a +4.64% offset. Use the speedometer error calculator to recheck for other indicated speeds, and the speedometer error guide for the full background.
Ground clearance change
The new tire's half-diameter changes ride height by +15.3 mm. Small differences are absorbed by suspension travel, but anything beyond ±10 mm can affect headlight aim, fender clearance and bump-stop margin. See the plus-sizing guide before committing.
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225/45 R18
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235/55 R17
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