Comparison
245/60 R18 vs 265/40 R20
Plus-sizing from 245/60 R18 to 265/40 R20 keeps overall diameter close to factory while opening room for a larger 20-inch wheel. This wheel and tire pairing swings rolling diameter far enough to feel on the road. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input.
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.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 265/40 R20 is 31.2 mm shorter than 245/60 R18, shifting the speedometer by -4.15%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-31.2 mm
-4.15%
Speedometer at 100
95.8 km/h
-4.15% error
Ground clearance
-15.6 mm
ride height delta
Sidewall change
-41.0 mm
revs/km: 442.1
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/compare/245-60-r18-vs-265-40-r20Detailed comparison
| Metric | 245/60 R18 | 265/40 R20 | Difference |
|---|---|---|---|
| Overall diameter | 751.2 mm | 720.0 mm | -31.2 mm (-4.15%) |
| Sidewall height | 147.0 mm | 106.0 mm | -41.0 mm |
| Circumference | 2.360 m | 2.262 m | -98.0 mm |
| Revs / km | 423.7 | 442.1 | +18.4 |
| Ground clearance | reference | -15.6 mm | -15.6 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 95.8 km/h | -4.15 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 95.8 km/h after switching to 265/40 R20 — a -4.15% 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 -15.6 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
245/60 R18
Back to
265/40 R20
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