Comparison
255/55 R18 vs 225/45 R17
Compared to 255/55 R18, 225/45 R17 is 103.4 mm shorter and changes the speedometer reading by -14.02%.
Current Tire
255/55R18
New Tire
225/45R17
255/55 R18
225/45 R17
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
-103.4 mm
-14.02%
Speedometer at 100
86.0 km/h
-14.02% error
Ground clearance
-51.7 mm
ride height delta
Sidewall change
-39.0 mm
revs/km: 501.8
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/compare/255-55-r18-vs-225-45-r17Detailed comparison
| Metric | 255/55 R18 | 225/45 R17 | Difference |
|---|---|---|---|
| Overall diameter | 737.7 mm | 634.3 mm | -103.4 mm (-14.02%) |
| Sidewall height | 140.3 mm | 101.3 mm | -39.0 mm |
| Circumference | 2.318 m | 1.993 m | -324.8 mm |
| Revs / km | 431.5 | 501.8 | +70.3 |
| Ground clearance | reference | -51.7 mm | -51.7 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 86.0 km/h | -14.02 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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255/55 R18
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225/45 R17