Comparison
225/40 R19 vs 245/45 R18
Minus-sizing from 225/40 R19 to 245/45 R18 pairs a smaller 18-inch wheel with more rubber between the rim and road. This wheel and tire pairing shifts overall diameter slightly from OEM. The taller sidewall adds cushioning over potholes and rougher roads, with a softer overall ride.
Expect a slight but noticeable shift in indicated speed compared to the original tires. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 245/45 R18 is 15.1 mm taller than 225/40 R19, shifting the speedometer by +2.28%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+15.1 mm
2.28%
Speedometer at 100
102.3 km/h
+2.28% error
Ground clearance
+7.6 mm
ride height delta
Sidewall change
+20.3 mm
revs/km: 469.7
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/compare/225-40-r19-vs-245-45-r18Detailed comparison
| Metric | 225/40 R19 | 245/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 662.6 mm | 677.7 mm | +15.1 mm (+2.28%) |
| Sidewall height | 90.0 mm | 110.3 mm | +20.3 mm |
| Circumference | 2.082 m | 2.129 m | +47.4 mm |
| Revs / km | 480.4 | 469.7 | -10.7 |
| Ground clearance | reference | +7.6 mm | +7.6 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 102.3 km/h | +2.28 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 102.3 km/h after switching to 245/45 R18 — a +2.28% 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 +7.6 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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245/45 R18
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