Comparison
255/45 R18 vs 295/35 R20
295/35 R20 is a plus-2 alternative to 255/45 R18 — the bigger wheel shows through a thinner sidewall. This swap 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. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 295/35 R20 is 27.8 mm taller than 255/45 R18, shifting the speedometer by +4.05%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+27.8 mm
4.05%
Speedometer at 100
104.0 km/h
+4.05% error
Ground clearance
+13.9 mm
ride height delta
Sidewall change
-11.5 mm
revs/km: 445.5
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/compare/255-45-r18-vs-295-35-r20Detailed comparison
| Metric | 255/45 R18 | 295/35 R20 | Difference |
|---|---|---|---|
| Overall diameter | 686.7 mm | 714.5 mm | +27.8 mm (+4.05%) |
| Sidewall height | 114.8 mm | 103.3 mm | -11.5 mm |
| Circumference | 2.157 m | 2.245 m | +87.3 mm |
| Revs / km | 463.5 | 445.5 | -18.0 |
| Ground clearance | reference | +13.9 mm | +13.9 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.0 km/h | +4.05 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 104.0 km/h after switching to 295/35 R20 — a +4.05% 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 +13.9 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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255/45 R18
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295/35 R20
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