Comparison
225/45 R18 vs 255/40 R19
Switching from 225/45 R18 to 255/40 R19 is a plus-1 upgrade that wraps a shorter sidewall around a larger 19-inch wheel. This swap noticeably changes overall diameter compared to OEM. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input.
The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 255/40 R19 is 26.9 mm taller than 225/45 R18, shifting the speedometer by +4.08%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+26.9 mm
4.08%
Speedometer at 100
104.1 km/h
+4.08% error
Ground clearance
+13.4 mm
ride height delta
Sidewall change
+0.8 mm
revs/km: 463.6
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/compare/225-45-r18-vs-255-40-r19Detailed comparison
| Metric | 225/45 R18 | 255/40 R19 | Difference |
|---|---|---|---|
| Overall diameter | 659.7 mm | 686.6 mm | +26.9 mm (+4.08%) |
| Sidewall height | 101.3 mm | 102.0 mm | +0.8 mm |
| Circumference | 2.073 m | 2.157 m | +84.5 mm |
| Revs / km | 482.5 | 463.6 | -18.9 |
| Ground clearance | reference | +13.4 mm | +13.4 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.1 km/h | +4.08 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 104.1 km/h after switching to 255/40 R19 — a +4.08% 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 +13.4 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
225/45 R18
Back to
255/40 R19
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