Comparison
225/50 R17 vs 275/40 R18
Plus-sizing from 225/50 R17 to 275/40 R18 keeps overall diameter close to factory while opening room for a larger 18-inch wheel. This wheel and tire pairing moves rolling diameter well outside the usual OEM tolerance. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides.
The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 275/40 R18 is 20.4 mm taller than 225/50 R17, shifting the speedometer by +3.11%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+20.4 mm
3.11%
Speedometer at 100
103.1 km/h
+3.11% error
Ground clearance
+10.2 mm
ride height delta
Sidewall change
-2.5 mm
revs/km: 470.0
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/compare/225-50-r17-vs-275-40-r18Detailed comparison
| Metric | 225/50 R17 | 275/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 656.8 mm | 677.2 mm | +20.4 mm (+3.11%) |
| Sidewall height | 112.5 mm | 110.0 mm | -2.5 mm |
| Circumference | 2.063 m | 2.127 m | +64.1 mm |
| Revs / km | 484.6 | 470.0 | -14.6 |
| Ground clearance | reference | +10.2 mm | +10.2 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.1 km/h | +3.11 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 103.1 km/h after switching to 275/40 R18 — a +3.11% 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 +10.2 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.
Back to
225/50 R17
Back to
275/40 R18
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