Comparison
225/55 R16 vs 265/40 R18
265/40 R18 is a plus-2 alternative to 225/55 R16 — the bigger wheel shows through a thinner sidewall. This tire combination trims or stretches rolling diameter by a small margin. The speedometer offset is small but measurable; worth keeping in mind if you watch the dash closely. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 265/40 R18 is 15.3 mm taller than 225/55 R16, shifting the speedometer by +2.34%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+15.3 mm
2.34%
Speedometer at 100
102.3 km/h
+2.34% error
Ground clearance
+7.7 mm
ride height delta
Sidewall change
-17.8 mm
revs/km: 475.7
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/compare/225-55-r16-vs-265-40-r18Detailed comparison
| Metric | 225/55 R16 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 653.9 mm | 669.2 mm | +15.3 mm (+2.34%) |
| Sidewall height | 123.8 mm | 106.0 mm | -17.8 mm |
| Circumference | 2.054 m | 2.102 m | +48.1 mm |
| Revs / km | 486.8 | 475.7 | -11.1 |
| Ground clearance | reference | +7.7 mm | +7.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 102.3 km/h | +2.34 km/h |
Verdict: excellent
Within ±3% — speedometer, ABS and traction control should behave normally.
Speedometer impact
At a true 100 km/h, your dashboard will read 102.3 km/h after switching to 265/40 R18 — a +2.34% 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 +7.7 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.
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225/55 R16
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265/40 R18
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