TireSizesFinder

285/50R20 vs 285/40R22

285/40R22 is 0.24 in (6.2 mm) shorter than 285/50R20, a −0.78% diameter difference. With the speedometer set for 285/50R20, an indicated 60 mph is 59.5 mph on 285/40R22.

Is this a safe swap?

Diameter difference −0.78%: under 1%

By overall diameter alone, 285/40R22 is a near match for 285/50R20; 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: 285/50R20 (31.22 in) vs 285/40R22 (30.98 in)285/50R2031.22 in × 11.22 in285/40R2230.98 in × 11.22 in
Side profile and tread width, drawn to the same scale.
285/50R20 vs 285/40R22 differences
Measurement285/50R20285/40R22Difference% diff
Overall diameter31.22 in (793.0 mm)30.98 in (786.8 mm)−0.24 in (−6.2 mm)−0.78%
Sidewall height5.61 in (142.5 mm)4.49 in (114.0 mm)−1.12 in (−28.5 mm)−20.00%
Section width11.22 in (285.0 mm)11.22 in (285.0 mm)0.00 in (0.0 mm)0.00%
Circumference98.08 in (2,491.3 mm)97.32 in (2,471.8 mm)−0.77 in (−19.5 mm)−0.78%
Revolutions per mile646651+5+0.79%
True speed with the speedometer calibrated for 285/50R20
IndicatedActual on 285/50R20Actual on 285/40R22Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.4 mph−0.6 mph

Ride-height change: 285/40R22 lowers the vehicle by 0.12 in (3.1 mm) at the axle (half the −6.2 mm diameter difference).

285/40R22 is 0.24 in shorter than 285/50R20 and the same width, a 0.78% difference in overall diameter.

With the speedometer calibrated for 285/50R20, an indicated 60 mph is actually 59.5 mph on 285/40R22, and revolutions per mile change from 646 to 651.

285/40R22 mounts on a 22-inch wheel, a plus-2 fitment from the 20-inch wheel of 285/50R20.

Size pages

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