Comparison
245/45 R20 vs 275/45 R20
275/45 R20 is a wider variation of 245/45 R20 on the same 20-inch rim, adding 30 mm of tread footprint. This sizing approach 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. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 275/45 R20 is 27.0 mm taller than 245/45 R20, shifting the speedometer by +3.71%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+27.0 mm
3.71%
Speedometer at 100
103.7 km/h
+3.71% error
Ground clearance
+13.5 mm
ride height delta
Sidewall change
+13.5 mm
revs/km: 421.3
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/compare/245-45-r20-vs-275-45-r20Detailed comparison
| Metric | 245/45 R20 | 275/45 R20 | Difference |
|---|---|---|---|
| Overall diameter | 728.5 mm | 755.5 mm | +27.0 mm (+3.71%) |
| Sidewall height | 110.3 mm | 123.8 mm | +13.5 mm |
| Circumference | 2.289 m | 2.373 m | +84.8 mm |
| Revs / km | 436.9 | 421.3 | -15.6 |
| Ground clearance | reference | +13.5 mm | +13.5 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 275/45 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 +13.5 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.
Back to
245/45 R20
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275/45 R20
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