Comparison
225/55 R16 vs 275/40 R18
Going from 225/55 R16 to 275/40 R18 steps up to a 18-inch rim while trimming sidewall to stay near OEM rolling diameter. This setup noticeably changes overall diameter compared to OEM.
Indicated speed will drift far enough that recalibration is worth considering. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. Many drivers pick this direction primarily for appearance — the bigger rim simply looks more aggressive. 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 23.3 mm taller than 225/55 R16, shifting the speedometer by +3.56%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+23.3 mm
3.56%
Speedometer at 100
103.6 km/h
+3.56% error
Ground clearance
+11.7 mm
ride height delta
Sidewall change
-13.8 mm
revs/km: 470.0
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/compare/225-55-r16-vs-275-40-r18Detailed comparison
| Metric | 225/55 R16 | 275/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 653.9 mm | 677.2 mm | +23.3 mm (+3.56%) |
| Sidewall height | 123.8 mm | 110.0 mm | -13.8 mm |
| Circumference | 2.054 m | 2.127 m | +73.2 mm |
| Revs / km | 486.8 | 470.0 | -16.7 |
| Ground clearance | reference | +11.7 mm | +11.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.6 km/h | +3.56 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 103.6 km/h after switching to 275/40 R18 — a +3.56% 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 +11.7 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
225/55 R16
Back to
275/40 R18
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