Comparison
225/45 R18 vs 245/45 R18
On the same 18-inch wheel, 245/45 R18 grows the section width by 20 mm versus 225/45 R18. This wheel and tire pairing trims or stretches rolling diameter by a small margin. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting.
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.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 245/45 R18 is 18.0 mm taller than 225/45 R18, shifting the speedometer by +2.73%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+18.0 mm
2.73%
Speedometer at 100
102.7 km/h
+2.73% error
Ground clearance
+9.0 mm
ride height delta
Sidewall change
+9.0 mm
revs/km: 469.7
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/compare/225-45-r18-vs-245-45-r18Detailed comparison
| Metric | 225/45 R18 | 245/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 659.7 mm | 677.7 mm | +18.0 mm (+2.73%) |
| Sidewall height | 101.3 mm | 110.3 mm | +9.0 mm |
| Circumference | 2.073 m | 2.129 m | +56.5 mm |
| Revs / km | 482.5 | 469.7 | -12.8 |
| Ground clearance | reference | +9.0 mm | +9.0 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 102.7 km/h | +2.73 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 102.7 km/h after switching to 245/45 R18 — a +2.73% 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 +9.0 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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225/45 R18
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245/45 R18
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