Comparison
235/50 R18 vs 265/40 R18
265/40 R18 is a lower-profile take on 235/50 R18 — same 18-inch wheel, shorter sidewall. This sizing approach moves rolling diameter well outside the usual OEM tolerance. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement.
Indicated speed will drift far enough that recalibration is worth considering. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeSuits drivers who value sharper steering and appearance over outright ride softness.
Quick math: 265/40 R18 is 23.0 mm shorter than 235/50 R18, shifting the speedometer by -3.32%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-23.0 mm
-3.32%
Speedometer at 100
96.7 km/h
-3.32% error
Ground clearance
-11.5 mm
ride height delta
Sidewall change
-11.5 mm
revs/km: 475.7
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/compare/235-50-r18-vs-265-40-r18Detailed comparison
| Metric | 235/50 R18 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 692.2 mm | 669.2 mm | -23.0 mm (-3.32%) |
| Sidewall height | 117.5 mm | 106.0 mm | -11.5 mm |
| Circumference | 2.175 m | 2.102 m | -72.3 mm |
| Revs / km | 459.9 | 475.7 | +15.8 |
| Ground clearance | reference | -11.5 mm | -11.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 96.7 km/h | -3.32 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 96.7 km/h after switching to 265/40 R18 — a -3.32% 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 -11.5 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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235/50 R18
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265/40 R18
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