Comparison
225/50 R18 vs 235/55 R18
235/55 R18 is a wider variation of 225/50 R18 on the same 18-inch rim, adding 10 mm of tread footprint. This setup noticeably changes overall diameter compared to OEM. 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. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 235/55 R18 is 33.5 mm taller than 225/50 R18, shifting the speedometer by +4.91%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+33.5 mm
4.91%
Speedometer at 100
104.9 km/h
+4.91% error
Ground clearance
+16.8 mm
ride height delta
Sidewall change
+16.8 mm
revs/km: 444.8
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/compare/225-50-r18-vs-235-55-r18Detailed comparison
| Metric | 225/50 R18 | 235/55 R18 | Difference |
|---|---|---|---|
| Overall diameter | 682.2 mm | 715.7 mm | +33.5 mm (+4.91%) |
| Sidewall height | 112.5 mm | 129.3 mm | +16.8 mm |
| Circumference | 2.143 m | 2.248 m | +105.2 mm |
| Revs / km | 466.6 | 444.8 | -21.8 |
| Ground clearance | reference | +16.8 mm | +16.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.9 km/h | +4.91 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 104.9 km/h after switching to 235/55 R18 — a +4.91% 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 +16.8 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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225/50 R18
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235/55 R18
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