Comparison
235/55 R17 vs 225/40 R18
Compared to 235/55 R17, 225/40 R18 is 53.1 mm shorter and changes the speedometer reading by -7.69%.
Current Tire
235/55R17
New Tire
225/40R18
235/55 R17
225/40 R18
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
-53.1 mm
-7.69%
Speedometer at 100
92.3 km/h
-7.69% error
Ground clearance
-26.5 mm
ride height delta
Sidewall change
-39.3 mm
revs/km: 499.5
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/compare/235-55-r17-vs-225-40-r18Detailed comparison
| Metric | 235/55 R17 | 225/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 690.3 mm | 637.2 mm | -53.1 mm (-7.69%) |
| Sidewall height | 129.3 mm | 90.0 mm | -39.3 mm |
| Circumference | 2.169 m | 2.002 m | -166.8 mm |
| Revs / km | 461.1 | 499.5 | +38.4 |
| Ground clearance | reference | -26.5 mm | -26.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 92.3 km/h | -7.69 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 R17
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225/40 R18