Comparison

215/60 R17 vs 215/40 R18

Compared to 215/60 R17, 215/40 R18 is 60.6 mm shorter and changes the speedometer reading by -8.79%.

Current Tire

215/60R17

New Tire

215/40R18
215/60 R17
215/40 R18

Ground line · scaled comparison

Not Recommended

Over 5% — speedometer & ABS may misread

Diameter change

-60.6 mm

-8.79%

Speedometer at 100

91.2 km/h

-8.79% error

Ground clearance

-30.3 mm

ride height delta

Sidewall change

-43.0 mm

revs/km: 505.9

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Detailed comparison

Metric215/60 R17215/40 R18Difference
Overall diameter689.8 mm629.2 mm-60.6 mm (-8.79%)
Sidewall height129.0 mm86.0 mm-43.0 mm
Circumference2.167 m1.977 m-190.4 mm
Revs / km461.5505.9+44.4
Ground clearancereference-30.3 mm-30.3 mm
Speedometer @ 100 km/h100.0 km/h91.2 km/h-8.79 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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215/60 R17

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215/40 R18

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Frequently asked questions

All 17″ sizes →All 18″ sizes →Speedometer error guide →Wheel offset guide →Plus-sizing guide →