Comparison
255/40 R18 vs 255/40 R19
Switching from 255/40 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 speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. The larger wheel shows more of the brake hardware and tightens up the wheel-gap look. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 255/40 R19 is 25.4 mm taller than 255/40 R18, shifting the speedometer by +3.84%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+25.4 mm
3.84%
Speedometer at 100
103.8 km/h
+3.84% error
Ground clearance
+12.7 mm
ride height delta
Sidewall change
0.0 mm
revs/km: 463.6
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/compare/255-40-r18-vs-255-40-r19Detailed comparison
| Metric | 255/40 R18 | 255/40 R19 | Difference |
|---|---|---|---|
| Overall diameter | 661.2 mm | 686.6 mm | +25.4 mm (+3.84%) |
| Sidewall height | 102.0 mm | 102.0 mm | 0.0 mm |
| Circumference | 2.077 m | 2.157 m | +79.8 mm |
| Revs / km | 481.4 | 463.6 | -17.8 |
| Ground clearance | reference | +12.7 mm | +12.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.8 km/h | +3.84 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 103.8 km/h after switching to 255/40 R19 — a +3.84% 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 +12.7 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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255/40 R18
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255/40 R19
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