Comparison
265/40 R20 vs 275/45 R20
275/45 R20 is a wider variation of 265/40 R20 on the same 20-inch rim, adding 10 mm of tread footprint. This wheel and tire pairing swings rolling diameter far enough to feel on the road. The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. Extra sidewall absorbs impacts more readily — a sensible bias for daily commuting and broken pavement. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 275/45 R20 is 35.5 mm taller than 265/40 R20, shifting the speedometer by +4.93%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+35.5 mm
4.93%
Speedometer at 100
104.9 km/h
+4.93% error
Ground clearance
+17.8 mm
ride height delta
Sidewall change
+17.8 mm
revs/km: 421.3
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/compare/265-40-r20-vs-275-45-r20Detailed comparison
| Metric | 265/40 R20 | 275/45 R20 | Difference |
|---|---|---|---|
| Overall diameter | 720.0 mm | 755.5 mm | +35.5 mm (+4.93%) |
| Sidewall height | 106.0 mm | 123.8 mm | +17.8 mm |
| Circumference | 2.262 m | 2.373 m | +111.5 mm |
| Revs / km | 442.1 | 421.3 | -20.8 |
| Ground clearance | reference | +17.8 mm | +17.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.9 km/h | +4.93 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 104.9 km/h after switching to 275/45 R20 — a +4.93% 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 +17.8 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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265/40 R20
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275/45 R20
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