255/65R18 vs 275/55R19

275/55R19 is 0.14 in (3.6 mm) shorter than 255/65R18, a −0.46% diameter difference. With the speedometer set for 255/65R18, an indicated 60 mph is 59.7 mph on 275/55R19.

Is this a safe swap?

Diameter difference −0.46%: under 1%

By overall diameter alone, 275/55R19 is a near match for 255/65R18; 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.

255/65R18 vs 275/55R19 differences
Measurement	255/65R18	275/55R19	Difference	% diff
Overall diameter	31.05 in (788.7 mm)	30.91 in (785.1 mm)	−0.14 in (−3.6 mm)	−0.46%
Sidewall height	6.53 in (165.8 mm)	5.95 in (151.3 mm)	−0.57 in (−14.5 mm)	−8.75%
Section width	10.04 in (255.0 mm)	10.83 in (275.0 mm)	+0.79 in (+20.0 mm)	+7.84%
Circumference	97.55 in (2,477.8 mm)	97.10 in (2,466.5 mm)	−0.45 in (−11.3 mm)	−0.46%
Revolutions per mile	650	652	+3	+0.46%

True speed with the speedometer calibrated for 255/65R18
Indicated	Actual on 255/65R18	Actual on 275/55R19	Difference
30 mph	30.0 mph	29.9 mph	−0.1 mph
60 mph	60.0 mph	59.7 mph	−0.3 mph
75 mph	75.0 mph	74.7 mph	−0.3 mph

Ride-height change: 275/55R19 lowers the vehicle by 0.07 in (1.8 mm) at the axle (half the −3.6 mm diameter difference).

275/55R19 is 0.14 in shorter than 255/65R18 and 20 mm wider, a 0.46% difference in overall diameter.

With the speedometer calibrated for 255/65R18, an indicated 60 mph is actually 59.7 mph on 275/55R19, and revolutions per mile change from 650 to 652.

275/55R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 255/65R18.

Size pages

Other comparisons with 255/65R18

Other comparisons with 275/55R19

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