Comparison
235/55 R18 vs 225/45 R17
Compared to 235/55 R18, 225/45 R17 is 81.4 mm shorter and changes the speedometer reading by -11.37%.
Current Tire
235/55R18
New Tire
225/45R17
235/55 R18
225/45 R17
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
-81.4 mm
-11.37%
Speedometer at 100
88.6 km/h
-11.37% error
Ground clearance
-40.7 mm
ride height delta
Sidewall change
-28.0 mm
revs/km: 501.8
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/compare/235-55-r18-vs-225-45-r17Detailed comparison
| Metric | 235/55 R18 | 225/45 R17 | Difference |
|---|---|---|---|
| Overall diameter | 715.7 mm | 634.3 mm | -81.4 mm (-11.37%) |
| Sidewall height | 129.3 mm | 101.3 mm | -28.0 mm |
| Circumference | 2.248 m | 1.993 m | -255.7 mm |
| Revs / km | 444.8 | 501.8 | +57.1 |
| Ground clearance | reference | -40.7 mm | -40.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 88.6 km/h | -11.37 km/h |
Verdict: danger
Over 5% diameter difference — likely to affect speedometer accuracy, ABS calibration and gearing. Not recommended without professional review.
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235/55 R18
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225/45 R17