TireSizesFinder

265/40R20 vs 255/30R22

255/30R22 is 0.32 in (8.2 mm) shorter than 265/40R20, a −1.14% diameter difference. With the speedometer set for 265/40R20, an indicated 60 mph is 59.3 mph on 255/30R22.

Is this a safe swap?

Diameter difference −1.14%: within the ±3% guideline

By overall diameter alone, 255/30R22 falls inside the ±3% range commonly used as a guideline when replacing 265/40R20. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 265/40R20 (28.35 in) vs 255/30R22 (28.02 in)265/40R2028.35 in × 10.43 in255/30R2228.02 in × 10.04 in
Side profile and tread width, drawn to the same scale.
265/40R20 vs 255/30R22 differences
Measurement265/40R20255/30R22Difference% diff
Overall diameter28.35 in (720.0 mm)28.02 in (711.8 mm)−0.32 in (−8.2 mm)−1.14%
Sidewall height4.17 in (106.0 mm)3.01 in (76.5 mm)−1.16 in (−29.5 mm)−27.83%
Section width10.43 in (265.0 mm)10.04 in (255.0 mm)−0.39 in (−10.0 mm)−3.77%
Circumference89.05 in (2,261.9 mm)88.04 in (2,236.2 mm)−1.01 in (−25.8 mm)−1.14%
Revolutions per mile711720+8+1.15%
True speed with the speedometer calibrated for 265/40R20
IndicatedActual on 265/40R20Actual on 255/30R22Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.3 mph−0.7 mph
75 mph75.0 mph74.1 mph−0.9 mph

Ride-height change: 255/30R22 lowers the vehicle by 0.16 in (4.1 mm) at the axle (half the −8.2 mm diameter difference).

255/30R22 is 0.32 in shorter than 265/40R20 and 10 mm narrower, a 1.14% difference in overall diameter.

With the speedometer calibrated for 265/40R20, an indicated 60 mph is actually 59.3 mph on 255/30R22, and revolutions per mile change from 711 to 720.

255/30R22 mounts on a 22-inch wheel, a plus-2 fitment from the 20-inch wheel of 265/40R20.

Size pages

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