Comparison

255/55 R18 vs 225/40 R19

Compared to 255/55 R18, 225/40 R19 is 75.1 mm shorter and changes the speedometer reading by -10.18%.

Current Tire

255/55R18

New Tire

225/40R19
255/55 R18
225/40 R19

Ground line · scaled comparison

Not Recommended

Over 5% — speedometer & ABS may misread

Diameter change

-75.1 mm

-10.18%

Speedometer at 100

89.8 km/h

-10.18% error

Ground clearance

-37.6 mm

ride height delta

Sidewall change

-50.3 mm

revs/km: 480.4

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Detailed comparison

Metric255/55 R18225/40 R19Difference
Overall diameter737.7 mm662.6 mm-75.1 mm (-10.18%)
Sidewall height140.3 mm90.0 mm-50.3 mm
Circumference2.318 m2.082 m-235.9 mm
Revs / km431.5480.4+48.9
Ground clearancereference-37.6 mm-37.6 mm
Speedometer @ 100 km/h100.0 km/h89.8 km/h-10.18 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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225/40 R19

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Frequently asked questions

All 18″ sizes →All 19″ sizes →Speedometer error guide →Wheel offset guide →Plus-sizing guide →