235/55R19 vs 255/55R19

255/55R19 is 0.87 in (22.0 mm) taller than 235/55R19, a +2.97% diameter difference. With the speedometer set for 235/55R19, an indicated 60 mph is 61.8 mph on 255/55R19.

Is this a safe swap?

Diameter difference +2.97%: within the ±3% guideline

By overall diameter alone, 255/55R19 falls inside the ±3% range commonly used as a guideline when replacing 235/55R19. 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.

235/55R19 vs 255/55R19 differences
Measurement	235/55R19	255/55R19	Difference	% diff
Overall diameter	29.18 in (741.1 mm)	30.04 in (763.1 mm)	+0.87 in (+22.0 mm)	+2.97%
Sidewall height	5.09 in (129.3 mm)	5.52 in (140.3 mm)	+0.43 in (+11.0 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	91.66 in (2,328.2 mm)	94.38 in (2,397.3 mm)	+2.72 in (+69.1 mm)	+2.97%
Revolutions per mile	691	671	−20	−2.88%

True speed with the speedometer calibrated for 235/55R19
Indicated	Actual on 235/55R19	Actual on 255/55R19	Difference
30 mph	30.0 mph	30.9 mph	+0.9 mph
60 mph	60.0 mph	61.8 mph	+1.8 mph
75 mph	75.0 mph	77.2 mph	+2.2 mph

Ride-height change: 255/55R19 raises the vehicle by 0.43 in (11.0 mm) at the axle (half the +22.0 mm diameter difference).

255/55R19 is 0.87 in taller than 235/55R19 and 20 mm wider, a 2.97% difference in overall diameter.

With the speedometer calibrated for 235/55R19, an indicated 60 mph is actually 61.8 mph on 255/55R19, and revolutions per mile change from 691 to 671.

Both sizes mount on 19-inch wheels.

Size pages

Other comparisons with 235/55R19

Other comparisons with 255/55R19

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