Comparison
245/45 R19 vs 255/40 R19
Stepping from 245/45 R19 to 255/40 R19 keeps the 19-inch wheel but widens the section by 10 mm. 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. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeReasonable performance-leaning swap as long as fender and suspension clearance check out.
Quick math: 255/40 R19 is 16.5 mm shorter than 245/45 R19, shifting the speedometer by -2.35%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-16.5 mm
-2.35%
Speedometer at 100
97.7 km/h
-2.35% error
Ground clearance
-8.3 mm
ride height delta
Sidewall change
-8.3 mm
revs/km: 463.6
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/compare/245-45-r19-vs-255-40-r19Detailed comparison
| Metric | 245/45 R19 | 255/40 R19 | Difference |
|---|---|---|---|
| Overall diameter | 703.1 mm | 686.6 mm | -16.5 mm (-2.35%) |
| Sidewall height | 110.3 mm | 102.0 mm | -8.3 mm |
| Circumference | 2.209 m | 2.157 m | -51.8 mm |
| Revs / km | 452.7 | 463.6 | +10.9 |
| Ground clearance | reference | -8.3 mm | -8.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 97.7 km/h | -2.35 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 97.7 km/h after switching to 255/40 R19 — a -2.35% 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 -8.3 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
245/45 R19
Back to
255/40 R19
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