Comparison
225/45 R18 vs 225/55 R17
Going from 225/45 R18 to 225/55 R17 is a minus-1 setup that adds sidewall on a smaller 17-inch wheel. This tire combination shifts overall diameter slightly from OEM. Expect a slight but noticeable shift in indicated speed compared to the original tires. More sidewall typically improves comfort and curb protection, especially on city streets. 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: 225/55 R17 is 19.6 mm taller than 225/45 R18, shifting the speedometer by +2.97%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+19.6 mm
2.97%
Speedometer at 100
103.0 km/h
+2.97% error
Ground clearance
+9.8 mm
ride height delta
Sidewall change
+22.5 mm
revs/km: 468.6
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/compare/225-45-r18-vs-225-55-r17Detailed comparison
| Metric | 225/45 R18 | 225/55 R17 | Difference |
|---|---|---|---|
| Overall diameter | 659.7 mm | 679.3 mm | +19.6 mm (+2.97%) |
| Sidewall height | 101.3 mm | 123.8 mm | +22.5 mm |
| Circumference | 2.073 m | 2.134 m | +61.6 mm |
| Revs / km | 482.5 | 468.6 | -13.9 |
| Ground clearance | reference | +9.8 mm | +9.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.0 km/h | +2.97 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 103.0 km/h after switching to 225/55 R17 — a +2.97% 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 +9.8 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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225/55 R17
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