Comparison
235/40 R18 vs 245/40 R19
Plus-sizing from 235/40 R18 to 245/40 R19 keeps overall diameter close to factory while opening room for a larger 19-inch wheel. This alternative fitment moves rolling diameter well outside the usual OEM tolerance. The dashboard speed will be significantly off — plan on recalibration before daily use. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. A diameter change beyond 5% is aggressive enough to influence ABS, traction control and gearing; treat it as a serious modification.
TakeRecommended only after a professional fitment check and speedometer recalibration.
Quick math: 245/40 R19 is 33.4 mm taller than 235/40 R18, shifting the speedometer by +5.18%.
Current Tire
New Tire
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
+33.4 mm
5.18%
Speedometer at 100
105.2 km/h
+5.18% error
Ground clearance
+16.7 mm
ride height delta
Sidewall change
+4.0 mm
revs/km: 469.1
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/compare/235-40-r18-vs-245-40-r19Detailed comparison
| Metric | 235/40 R18 | 245/40 R19 | Difference |
|---|---|---|---|
| Overall diameter | 645.2 mm | 678.6 mm | +33.4 mm (+5.18%) |
| Sidewall height | 94.0 mm | 98.0 mm | +4.0 mm |
| Circumference | 2.027 m | 2.132 m | +104.9 mm |
| Revs / km | 493.4 | 469.1 | -24.3 |
| Ground clearance | reference | +16.7 mm | +16.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 105.2 km/h | +5.18 km/h |
Verdict: danger
Over 5% diameter difference — likely to affect speedometer accuracy, ABS calibration and gearing. Not recommended without professional review.
Speedometer impact
At a true 100 km/h, your dashboard will read 105.2 km/h after switching to 245/40 R19 — a +5.18% 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 +16.7 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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235/40 R18
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245/40 R19
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