245/30R19 vs 255/30R19

255/30R19 is 0.24 in (6.0 mm) taller than 245/30R19, a +0.95% diameter difference. With the speedometer set for 245/30R19, an indicated 60 mph is 60.6 mph on 255/30R19.

Is this a safe swap?

Diameter difference +0.95%: under 1%

By overall diameter alone, 255/30R19 is a near match for 245/30R19; 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.

245/30R19 vs 255/30R19 differences
Measurement	245/30R19	255/30R19	Difference	% diff
Overall diameter	24.79 in (629.6 mm)	25.02 in (635.6 mm)	+0.24 in (+6.0 mm)	+0.95%
Sidewall height	2.89 in (73.5 mm)	3.01 in (76.5 mm)	+0.12 in (+3.0 mm)	+4.08%
Section width	9.65 in (245.0 mm)	10.04 in (255.0 mm)	+0.39 in (+10.0 mm)	+4.08%
Circumference	77.87 in (1,977.9 mm)	78.61 in (1,996.8 mm)	+0.74 in (+18.8 mm)	+0.95%
Revolutions per mile	814	806	−8	−0.94%

True speed with the speedometer calibrated for 245/30R19
Indicated	Actual on 245/30R19	Actual on 255/30R19	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.6 mph	+0.6 mph
75 mph	75.0 mph	75.7 mph	+0.7 mph

Ride-height change: 255/30R19 raises the vehicle by 0.12 in (3.0 mm) at the axle (half the +6.0 mm diameter difference).

255/30R19 is 0.24 in taller than 245/30R19 and 10 mm wider, a 0.95% difference in overall diameter.

With the speedometer calibrated for 245/30R19, an indicated 60 mph is actually 60.6 mph on 255/30R19, and revolutions per mile change from 814 to 806.

Both sizes mount on 19-inch wheels.

Size pages

Other comparisons with 245/30R19

Other comparisons with 255/30R19

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