Comparison
215/40 R18 vs 225/55 R16
Switching from 215/40 R18 to 225/55 R16 steps down to a 16-inch wheel — a familiar move for winter and dedicated all-terrain sets. This alternative fitment noticeably changes overall diameter compared to OEM. The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. Extra sidewall absorbs impacts more readily — a sensible bias for daily commuting and broken pavement. 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: 225/55 R16 is 24.7 mm taller than 215/40 R18, shifting the speedometer by +3.93%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+24.7 mm
3.93%
Speedometer at 100
103.9 km/h
+3.93% error
Ground clearance
+12.3 mm
ride height delta
Sidewall change
+37.8 mm
revs/km: 486.8
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/compare/215-40-r18-vs-225-55-r16Detailed comparison
| Metric | 215/40 R18 | 225/55 R16 | Difference |
|---|---|---|---|
| Overall diameter | 629.2 mm | 653.9 mm | +24.7 mm (+3.93%) |
| Sidewall height | 86.0 mm | 123.8 mm | +37.8 mm |
| Circumference | 1.977 m | 2.054 m | +77.6 mm |
| Revs / km | 505.9 | 486.8 | -19.1 |
| Ground clearance | reference | +12.3 mm | +12.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.9 km/h | +3.93 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 103.9 km/h after switching to 225/55 R16 — a +3.93% 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 +12.3 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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215/40 R18
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225/55 R16
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