Comparison
235/45 R18 vs 265/35 R20
265/35 R20 is a plus-2 alternative to 235/45 R18 — the bigger wheel shows through a thinner sidewall. This alternative fitment noticeably changes overall diameter compared to OEM.
The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting. 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: 265/35 R20 is 24.8 mm taller than 235/45 R18, shifting the speedometer by +3.71%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+24.8 mm
3.71%
Speedometer at 100
103.7 km/h
+3.71% error
Ground clearance
+12.4 mm
ride height delta
Sidewall change
-13.0 mm
revs/km: 459.0
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/compare/235-45-r18-vs-265-35-r20Detailed comparison
| Metric | 235/45 R18 | 265/35 R20 | Difference |
|---|---|---|---|
| Overall diameter | 668.7 mm | 693.5 mm | +24.8 mm (+3.71%) |
| Sidewall height | 105.8 mm | 92.8 mm | -13.0 mm |
| Circumference | 2.101 m | 2.179 m | +77.9 mm |
| Revs / km | 476.0 | 459.0 | -17.0 |
| Ground clearance | reference | +12.4 mm | +12.4 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.7 km/h | +3.71 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 103.7 km/h after switching to 265/35 R20 — a +3.71% 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 +12.4 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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235/45 R18
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265/35 R20
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