Comparison
225/40 R19 vs 245/40 R18
Going from 225/40 R19 to 245/40 R18 is a minus-1 setup that adds sidewall on a smaller 18-inch wheel. This tire combination lands within OEM rolling-diameter tolerance. The speedometer offset is mild and well inside what most cars can tolerate without recalibration. 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.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 245/40 R18 is 9.4 mm shorter than 225/40 R19, shifting the speedometer by -1.42%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-9.4 mm
-1.42%
Speedometer at 100
98.6 km/h
-1.42% error
Ground clearance
-4.7 mm
ride height delta
Sidewall change
+8.0 mm
revs/km: 487.3
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/compare/225-40-r19-vs-245-40-r18Detailed comparison
| Metric | 225/40 R19 | 245/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 662.6 mm | 653.2 mm | -9.4 mm (-1.42%) |
| Sidewall height | 90.0 mm | 98.0 mm | +8.0 mm |
| Circumference | 2.082 m | 2.052 m | -29.5 mm |
| Revs / km | 480.4 | 487.3 | +6.9 |
| Ground clearance | reference | -4.7 mm | -4.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.6 km/h | -1.42 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 98.6 km/h after switching to 245/40 R18 — a -1.42% 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 -4.7 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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225/40 R19
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245/40 R18
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