TireSizesFinder

255/55R18 vs 235/55R19

235/55R19 is 0.13 in (3.4 mm) taller than 255/55R18, a +0.46% diameter difference. With the speedometer set for 255/55R18, an indicated 60 mph is 60.3 mph on 235/55R19.

Is this a safe swap?

Diameter difference +0.46%: under 1%

By overall diameter alone, 235/55R19 is a near match for 255/55R18; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 255/55R18 (29.04 in) vs 235/55R19 (29.18 in)255/55R1829.04 in × 10.04 in235/55R1929.18 in × 9.25 in
Side profile and tread width, drawn to the same scale.
255/55R18 vs 235/55R19 differences
Measurement255/55R18235/55R19Difference% diff
Overall diameter29.04 in (737.7 mm)29.18 in (741.1 mm)+0.13 in (+3.4 mm)+0.46%
Sidewall height5.52 in (140.3 mm)5.09 in (129.3 mm)−0.43 in (−11.0 mm)−7.84%
Section width10.04 in (255.0 mm)9.25 in (235.0 mm)−0.79 in (−20.0 mm)−7.84%
Circumference91.24 in (2,317.6 mm)91.66 in (2,328.2 mm)+0.42 in (+10.7 mm)+0.46%
Revolutions per mile694691−3−0.46%
True speed with the speedometer calibrated for 255/55R18
IndicatedActual on 255/55R18Actual on 235/55R19Difference
30 mph30.0 mph30.1 mph+0.1 mph
60 mph60.0 mph60.3 mph+0.3 mph
75 mph75.0 mph75.3 mph+0.3 mph

Ride-height change: 235/55R19 raises the vehicle by 0.07 in (1.7 mm) at the axle (half the +3.4 mm diameter difference).

235/55R19 is 0.13 in taller than 255/55R18 and 20 mm narrower, a 0.46% difference in overall diameter.

With the speedometer calibrated for 255/55R18, an indicated 60 mph is actually 60.3 mph on 235/55R19, and revolutions per mile change from 694 to 691.

235/55R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 255/55R18.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.