Comparison
245/40 R19 vs 255/45 R19
On the same 19-inch wheel, 255/45 R19 grows the section width by 10 mm versus 245/40 R19. This alternative fitment noticeably changes overall diameter compared to OEM. More sidewall typically improves comfort and curb protection, especially on city streets.
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.
TakeReasonable performance-leaning swap as long as fender and suspension clearance check out.
Quick math: 255/45 R19 is 33.5 mm taller than 245/40 R19, shifting the speedometer by +4.94%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+33.5 mm
4.94%
Speedometer at 100
104.9 km/h
+4.94% error
Ground clearance
+16.8 mm
ride height delta
Sidewall change
+16.8 mm
revs/km: 447.0
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/compare/245-40-r19-vs-255-45-r19Detailed comparison
| Metric | 245/40 R19 | 255/45 R19 | Difference |
|---|---|---|---|
| Overall diameter | 678.6 mm | 712.1 mm | +33.5 mm (+4.94%) |
| Sidewall height | 98.0 mm | 114.8 mm | +16.8 mm |
| Circumference | 2.132 m | 2.237 m | +105.2 mm |
| Revs / km | 469.1 | 447.0 | -22.1 |
| Ground clearance | reference | +16.8 mm | +16.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.9 km/h | +4.94 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 104.9 km/h after switching to 255/45 R19 — a +4.94% 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 +16.8 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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245/40 R19
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255/45 R19
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