TireSizesFinder

255/55R18 vs 225/55R19

225/55R19 is 0.30 in (7.6 mm) shorter than 255/55R18, a −1.03% diameter difference. With the speedometer set for 255/55R18, an indicated 60 mph is 59.4 mph on 225/55R19.

Is this a safe swap?

Diameter difference −1.03%: within the ±3% guideline

By overall diameter alone, 225/55R19 falls inside the ±3% range commonly used as a guideline when replacing 255/55R18. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 255/55R18 (29.04 in) vs 225/55R19 (28.74 in)255/55R1829.04 in × 10.04 in225/55R1928.74 in × 8.86 in
Side profile and tread width, drawn to the same scale.
255/55R18 vs 225/55R19 differences
Measurement255/55R18225/55R19Difference% diff
Overall diameter29.04 in (737.7 mm)28.74 in (730.1 mm)−0.30 in (−7.6 mm)−1.03%
Sidewall height5.52 in (140.3 mm)4.87 in (123.8 mm)−0.65 in (−16.5 mm)−11.76%
Section width10.04 in (255.0 mm)8.86 in (225.0 mm)−1.18 in (−30.0 mm)−11.76%
Circumference91.24 in (2,317.6 mm)90.30 in (2,293.7 mm)−0.94 in (−23.9 mm)−1.03%
Revolutions per mile694702+7+1.04%
True speed with the speedometer calibrated for 255/55R18
IndicatedActual on 255/55R18Actual on 225/55R19Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.4 mph−0.6 mph
75 mph75.0 mph74.2 mph−0.8 mph

Ride-height change: 225/55R19 lowers the vehicle by 0.15 in (3.8 mm) at the axle (half the −7.6 mm diameter difference).

225/55R19 is 0.30 in shorter than 255/55R18 and 30 mm narrower, a 1.03% difference in overall diameter.

With the speedometer calibrated for 255/55R18, an indicated 60 mph is actually 59.4 mph on 225/55R19, and revolutions per mile change from 694 to 702.

225/55R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 255/55R18.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.