Comparison
255/45 R18 vs 225/45 R17
Compared to 255/45 R18, 225/45 R17 is 52.4 mm shorter and changes the speedometer reading by -7.63%.
Current Tire
255/45R18
New Tire
225/45R17
255/45 R18
225/45 R17
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
-52.4 mm
-7.63%
Speedometer at 100
92.4 km/h
-7.63% error
Ground clearance
-26.2 mm
ride height delta
Sidewall change
-13.5 mm
revs/km: 501.8
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/compare/255-45-r18-vs-225-45-r17Detailed comparison
| Metric | 255/45 R18 | 225/45 R17 | Difference |
|---|---|---|---|
| Overall diameter | 686.7 mm | 634.3 mm | -52.4 mm (-7.63%) |
| Sidewall height | 114.8 mm | 101.3 mm | -13.5 mm |
| Circumference | 2.157 m | 1.993 m | -164.6 mm |
| Revs / km | 463.5 | 501.8 | +38.3 |
| Ground clearance | reference | -26.2 mm | -26.2 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 92.4 km/h | -7.63 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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255/45 R18
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225/45 R17