Comparison
235/65 R16 vs 255/55 R18
Going from 235/65 R16 to 255/55 R18 steps up to a 18-inch rim while trimming sidewall to stay near OEM rolling diameter. This setup swings rolling diameter far enough to feel on the road. 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.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 255/55 R18 is 25.8 mm taller than 235/65 R16, shifting the speedometer by +3.62%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+25.8 mm
3.62%
Speedometer at 100
103.6 km/h
+3.62% error
Ground clearance
+12.9 mm
ride height delta
Sidewall change
-12.5 mm
revs/km: 431.5
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/compare/235-65-r16-vs-255-55-r18Detailed comparison
| Metric | 235/65 R16 | 255/55 R18 | Difference |
|---|---|---|---|
| Overall diameter | 711.9 mm | 737.7 mm | +25.8 mm (+3.62%) |
| Sidewall height | 152.8 mm | 140.3 mm | -12.5 mm |
| Circumference | 2.236 m | 2.318 m | +81.1 mm |
| Revs / km | 447.1 | 431.5 | -15.6 |
| Ground clearance | reference | +12.9 mm | +12.9 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.6 km/h | +3.62 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 255/55 R18 — a +3.62% 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 +12.9 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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235/65 R16
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255/55 R18
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