Comparison
215/55 R17 vs 215/40 R18
Compared to 215/55 R17, 215/40 R18 is 39.1 mm shorter and changes the speedometer reading by -5.85%.
Current Tire
215/55R17
New Tire
215/40R18
215/55 R17
215/40 R18
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
-39.1 mm
-5.85%
Speedometer at 100
94.1 km/h
-5.85% error
Ground clearance
-19.5 mm
ride height delta
Sidewall change
-32.3 mm
revs/km: 505.9
Permalink for this comparison:
/compare/215-55-r17-vs-215-40-r18Detailed comparison
| Metric | 215/55 R17 | 215/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 668.3 mm | 629.2 mm | -39.1 mm (-5.85%) |
| Sidewall height | 118.3 mm | 86.0 mm | -32.3 mm |
| Circumference | 2.100 m | 1.977 m | -122.8 mm |
| Revs / km | 476.3 | 505.9 | +29.6 |
| Ground clearance | reference | -19.5 mm | -19.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 94.1 km/h | -5.85 km/h |
Verdict: danger
Over 5% diameter difference — likely to affect speedometer accuracy, ABS calibration and gearing. Not recommended without professional review.
Back to
215/55 R17
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215/40 R18