TireSizesFinder

265/35R19 vs 255/30R20

255/30R20 is 0.28 in (7.1 mm) shorter than 265/35R19, a −1.06% diameter difference. With the speedometer set for 265/35R19, an indicated 60 mph is 59.4 mph on 255/30R20.

Is this a safe swap?

Diameter difference −1.06%: within the ±3% guideline

By overall diameter alone, 255/30R20 falls inside the ±3% range commonly used as a guideline when replacing 265/35R19. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 265/35R19 (26.30 in) vs 255/30R20 (26.02 in)265/35R1926.30 in × 10.43 in255/30R2026.02 in × 10.04 in
Side profile and tread width, drawn to the same scale.
265/35R19 vs 255/30R20 differences
Measurement265/35R19255/30R20Difference% diff
Overall diameter26.30 in (668.1 mm)26.02 in (661.0 mm)−0.28 in (−7.1 mm)−1.06%
Sidewall height3.65 in (92.8 mm)3.01 in (76.5 mm)−0.64 in (−16.2 mm)−17.52%
Section width10.43 in (265.0 mm)10.04 in (255.0 mm)−0.39 in (−10.0 mm)−3.77%
Circumference82.63 in (2,098.9 mm)81.76 in (2,076.6 mm)−0.88 in (−22.3 mm)−1.06%
Revolutions per mile767775+8+1.07%
True speed with the speedometer calibrated for 265/35R19
IndicatedActual on 265/35R19Actual on 255/30R20Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.4 mph−0.6 mph
75 mph75.0 mph74.2 mph−0.8 mph

Ride-height change: 255/30R20 lowers the vehicle by 0.14 in (3.5 mm) at the axle (half the −7.1 mm diameter difference).

255/30R20 is 0.28 in shorter than 265/35R19 and 10 mm narrower, a 1.06% difference in overall diameter.

With the speedometer calibrated for 265/35R19, an indicated 60 mph is actually 59.4 mph on 255/30R20, and revolutions per mile change from 767 to 775.

255/30R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 265/35R19.

Size pages

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