255/50R18 vs 225/50R19

225/50R19 is 0.18 in (4.6 mm) shorter than 255/50R18, a −0.65% diameter difference. With the speedometer set for 255/50R18, an indicated 60 mph is 59.6 mph on 225/50R19.

Is this a safe swap?

Diameter difference −0.65%: under 1%

By overall diameter alone, 225/50R19 is a near match for 255/50R18; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

255/50R18 vs 225/50R19 differences
Measurement	255/50R18	225/50R19	Difference	% diff
Overall diameter	28.04 in (712.2 mm)	27.86 in (707.6 mm)	−0.18 in (−4.6 mm)	−0.65%
Sidewall height	5.02 in (127.5 mm)	4.43 in (112.5 mm)	−0.59 in (−15.0 mm)	−11.76%
Section width	10.04 in (255.0 mm)	8.86 in (225.0 mm)	−1.18 in (−30.0 mm)	−11.76%
Circumference	88.09 in (2,237.4 mm)	87.52 in (2,223.0 mm)	−0.57 in (−14.5 mm)	−0.65%
Revolutions per mile	719	724	+5	+0.65%

True speed with the speedometer calibrated for 255/50R18
Indicated	Actual on 255/50R18	Actual on 225/50R19	Difference
30 mph	30.0 mph	29.8 mph	−0.2 mph
60 mph	60.0 mph	59.6 mph	−0.4 mph
75 mph	75.0 mph	74.5 mph	−0.5 mph

Ride-height change: 225/50R19 lowers the vehicle by 0.09 in (2.3 mm) at the axle (half the −4.6 mm diameter difference).

225/50R19 is 0.18 in shorter than 255/50R18 and 30 mm narrower, a 0.65% difference in overall diameter.

With the speedometer calibrated for 255/50R18, an indicated 60 mph is actually 59.6 mph on 225/50R19, and revolutions per mile change from 719 to 724.

225/50R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 255/50R18.

Size pages

Other comparisons with 255/50R18

Other comparisons with 225/50R19

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.