Comparison
225/50 R17 vs 255/45 R18
255/45 R18 is a plus-1 alternative to 225/50 R17 — the bigger wheel shows through a thinner sidewall. This setup moves rolling diameter well outside the usual OEM tolerance. Indicated speed will drift far enough that recalibration is worth considering. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input. 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: 255/45 R18 is 29.9 mm taller than 225/50 R17, shifting the speedometer by +4.55%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+29.9 mm
4.55%
Speedometer at 100
104.6 km/h
+4.55% error
Ground clearance
+15.0 mm
ride height delta
Sidewall change
+2.3 mm
revs/km: 463.5
Permalink for this comparison:
/compare/225-50-r17-vs-255-45-r18Detailed comparison
| Metric | 225/50 R17 | 255/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 656.8 mm | 686.7 mm | +29.9 mm (+4.55%) |
| Sidewall height | 112.5 mm | 114.8 mm | +2.3 mm |
| Circumference | 2.063 m | 2.157 m | +93.9 mm |
| Revs / km | 484.6 | 463.5 | -21.1 |
| Ground clearance | reference | +15.0 mm | +15.0 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.6 km/h | +4.55 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 104.6 km/h after switching to 255/45 R18 — a +4.55% 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 +15.0 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
225/50 R17
Back to
255/45 R18
Drivers also compare
Closely-related fitments and plus-size swaps for 225/50 R17 and 255/45 R18.
225/50 R18 vs 255/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.66%
225/50 R17 vs 245/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 0.69%
235/50 R18 vs 255/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.79%
245/45 R18 vs 255/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.33%
255/45 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.38%
215/50 R17 vs 225/50 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.55%
215/55 R17 vs 225/50 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.72%
225/50 R17 vs 235/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 2.06%
Related topics