TireSizesFinder

285/35R19 vs 255/35R20

255/35R20 is 0.17 in (4.4 mm) taller than 285/35R19, a +0.65% diameter difference. With the speedometer set for 285/35R19, an indicated 60 mph is 60.4 mph on 255/35R20.

Is this a safe swap?

Diameter difference +0.65%: under 1%

By overall diameter alone, 255/35R20 is a near match for 285/35R19; 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: 285/35R19 (26.85 in) vs 255/35R20 (27.03 in)285/35R1926.85 in × 11.22 in255/35R2027.03 in × 10.04 in
Side profile and tread width, drawn to the same scale.
285/35R19 vs 255/35R20 differences
Measurement285/35R19255/35R20Difference% diff
Overall diameter26.85 in (682.1 mm)27.03 in (686.5 mm)+0.17 in (+4.4 mm)+0.65%
Sidewall height3.93 in (99.8 mm)3.51 in (89.3 mm)−0.41 in (−10.5 mm)−10.53%
Section width11.22 in (285.0 mm)10.04 in (255.0 mm)−1.18 in (−30.0 mm)−10.53%
Circumference84.37 in (2,142.9 mm)84.91 in (2,156.7 mm)+0.54 in (+13.8 mm)+0.65%
Revolutions per mile751746−5−0.64%
True speed with the speedometer calibrated for 285/35R19
IndicatedActual on 285/35R19Actual on 255/35R20Difference
30 mph30.0 mph30.2 mph+0.2 mph
60 mph60.0 mph60.4 mph+0.4 mph
75 mph75.0 mph75.5 mph+0.5 mph

Ride-height change: 255/35R20 raises the vehicle by 0.09 in (2.2 mm) at the axle (half the +4.4 mm diameter difference).

255/35R20 is 0.17 in taller than 285/35R19 and 30 mm narrower, a 0.65% difference in overall diameter.

With the speedometer calibrated for 285/35R19, an indicated 60 mph is actually 60.4 mph on 255/35R20, and revolutions per mile change from 751 to 746.

255/35R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 285/35R19.

Size pages

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