Comparison
235/55 R18 vs 265/35 R20
Plus-sizing from 235/55 R18 to 265/35 R20 keeps overall diameter close to factory while opening room for a larger 20-inch wheel. This alternative fitment noticeably changes overall diameter compared to OEM. 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: 265/35 R20 is 22.2 mm shorter than 235/55 R18, shifting the speedometer by -3.10%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-22.2 mm
-3.10%
Speedometer at 100
96.9 km/h
-3.10% error
Ground clearance
-11.1 mm
ride height delta
Sidewall change
-36.5 mm
revs/km: 459.0
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/compare/235-55-r18-vs-265-35-r20Detailed comparison
| Metric | 235/55 R18 | 265/35 R20 | Difference |
|---|---|---|---|
| Overall diameter | 715.7 mm | 693.5 mm | -22.2 mm (-3.10%) |
| Sidewall height | 129.3 mm | 92.8 mm | -36.5 mm |
| Circumference | 2.248 m | 2.179 m | -69.7 mm |
| Revs / km | 444.8 | 459.0 | +14.2 |
| Ground clearance | reference | -11.1 mm | -11.1 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 96.9 km/h | -3.10 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 96.9 km/h after switching to 265/35 R20 — a -3.10% 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 -11.1 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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235/55 R18
Back to
265/35 R20
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