Comparison
225/60 R17 vs 275/40 R18
Switching from 225/60 R17 to 275/40 R18 is a plus-1 upgrade that wraps a shorter sidewall around a larger 18-inch wheel. This alternative fitment swings rolling diameter far enough to feel on the road. The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 275/40 R18 is 24.6 mm shorter than 225/60 R17, shifting the speedometer by -3.51%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-24.6 mm
-3.51%
Speedometer at 100
96.5 km/h
-3.51% error
Ground clearance
-12.3 mm
ride height delta
Sidewall change
-25.0 mm
revs/km: 470.0
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/compare/225-60-r17-vs-275-40-r18Detailed comparison
| Metric | 225/60 R17 | 275/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 701.8 mm | 677.2 mm | -24.6 mm (-3.51%) |
| Sidewall height | 135.0 mm | 110.0 mm | -25.0 mm |
| Circumference | 2.205 m | 2.127 m | -77.3 mm |
| Revs / km | 453.6 | 470.0 | +16.5 |
| Ground clearance | reference | -12.3 mm | -12.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 96.5 km/h | -3.51 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 96.5 km/h after switching to 275/40 R18 — a -3.51% 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.
Back to
225/60 R17
Back to
275/40 R18
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