235/50R19 vs 255/50R19

255/50R19 is 0.79 in (20.0 mm) taller than 235/50R19, a +2.79% diameter difference. With the speedometer set for 235/50R19, an indicated 60 mph is 61.7 mph on 255/50R19.

Is this a safe swap?

Diameter difference +2.79%: within the ±3% guideline

By overall diameter alone, 255/50R19 falls inside the ±3% range commonly used as a guideline when replacing 235/50R19. 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.

235/50R19 vs 255/50R19 differences
Measurement	235/50R19	255/50R19	Difference	% diff
Overall diameter	28.25 in (717.6 mm)	29.04 in (737.6 mm)	+0.79 in (+20.0 mm)	+2.79%
Sidewall height	4.63 in (117.5 mm)	5.02 in (127.5 mm)	+0.39 in (+10.0 mm)	+8.51%
Section width	9.25 in (235.0 mm)	10.04 in (255.0 mm)	+0.79 in (+20.0 mm)	+8.51%
Circumference	88.76 in (2,254.4 mm)	91.23 in (2,317.2 mm)	+2.47 in (+62.8 mm)	+2.79%
Revolutions per mile	714	695	−19	−2.71%

True speed with the speedometer calibrated for 235/50R19
Indicated	Actual on 235/50R19	Actual on 255/50R19	Difference
30 mph	30.0 mph	30.8 mph	+0.8 mph
60 mph	60.0 mph	61.7 mph	+1.7 mph
75 mph	75.0 mph	77.1 mph	+2.1 mph

Ride-height change: 255/50R19 raises the vehicle by 0.39 in (10.0 mm) at the axle (half the +20.0 mm diameter difference).

255/50R19 is 0.79 in taller than 235/50R19 and 20 mm wider, a 2.79% difference in overall diameter.

With the speedometer calibrated for 235/50R19, an indicated 60 mph is actually 61.7 mph on 255/50R19, and revolutions per mile change from 714 to 695.

Both sizes mount on 19-inch wheels.

Size pages

Other comparisons with 235/50R19

Other comparisons with 255/50R19

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