Comparison
225/55 R18 vs 255/35 R20
Plus-sizing from 225/55 R18 to 255/35 R20 keeps overall diameter close to factory while opening room for a larger 20-inch wheel. This tire combination moves rolling diameter a touch off the original spec. The speedometer offset is small but measurable; worth keeping in mind if you watch the dash closely. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 255/35 R20 is 18.2 mm shorter than 225/55 R18, shifting the speedometer by -2.58%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-18.2 mm
-2.58%
Speedometer at 100
97.4 km/h
-2.58% error
Ground clearance
-9.1 mm
ride height delta
Sidewall change
-34.5 mm
revs/km: 463.7
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/compare/225-55-r18-vs-255-35-r20Detailed comparison
| Metric | 225/55 R18 | 255/35 R20 | Difference |
|---|---|---|---|
| Overall diameter | 704.7 mm | 686.5 mm | -18.2 mm (-2.58%) |
| Sidewall height | 123.8 mm | 89.3 mm | -34.5 mm |
| Circumference | 2.214 m | 2.157 m | -57.2 mm |
| Revs / km | 451.7 | 463.7 | +12.0 |
| Ground clearance | reference | -9.1 mm | -9.1 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 97.4 km/h | -2.58 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 255/35 R20 — a -2.58% 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 -9.1 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
225/55 R18
Back to
255/35 R20
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