Comparison
225/45 R18 vs 245/45 R17
Minus-sizing from 225/45 R18 to 245/45 R17 pairs a smaller 17-inch wheel with more rubber between the rim and road. This setup preserves rolling diameter within a hair of the original. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance.
Speedometer drift stays small enough that most drivers won't notice it day to day. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.
Quick math: 245/45 R17 is 7.4 mm shorter than 225/45 R18, shifting the speedometer by -1.12%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-7.4 mm
-1.12%
Speedometer at 100
98.9 km/h
-1.12% error
Ground clearance
-3.7 mm
ride height delta
Sidewall change
+9.0 mm
revs/km: 488.0
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/compare/225-45-r18-vs-245-45-r17Detailed comparison
| Metric | 225/45 R18 | 245/45 R17 | Difference |
|---|---|---|---|
| Overall diameter | 659.7 mm | 652.3 mm | -7.4 mm (-1.12%) |
| Sidewall height | 101.3 mm | 110.3 mm | +9.0 mm |
| Circumference | 2.073 m | 2.049 m | -23.2 mm |
| Revs / km | 482.5 | 488.0 | +5.5 |
| Ground clearance | reference | -3.7 mm | -3.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.9 km/h | -1.12 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 98.9 km/h after switching to 245/45 R17 — a -1.12% 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 -3.7 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.
Back to
225/45 R18
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245/45 R17
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