Comparison
235/60 R18 vs 265/40 R20
Plus-sizing from 235/60 R18 to 265/40 R20 keeps overall diameter close to factory while opening room for a larger 20-inch wheel. 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. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff. The larger wheel shows more of the brake hardware and tightens up the wheel-gap look. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 265/40 R20 is 19.2 mm shorter than 235/60 R18, shifting the speedometer by -2.60%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-19.2 mm
-2.60%
Speedometer at 100
97.4 km/h
-2.60% error
Ground clearance
-9.6 mm
ride height delta
Sidewall change
-35.0 mm
revs/km: 442.1
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/compare/235-60-r18-vs-265-40-r20Detailed comparison
| Metric | 235/60 R18 | 265/40 R20 | Difference |
|---|---|---|---|
| Overall diameter | 739.2 mm | 720.0 mm | -19.2 mm (-2.60%) |
| Sidewall height | 141.0 mm | 106.0 mm | -35.0 mm |
| Circumference | 2.322 m | 2.262 m | -60.3 mm |
| Revs / km | 430.6 | 442.1 | +11.5 |
| Ground clearance | reference | -9.6 mm | -9.6 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 97.4 km/h | -2.60 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 97.4 km/h after switching to 265/40 R20 — a -2.60% 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 -9.6 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.
Back to
235/60 R18
Back to
265/40 R20
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