TireSizesFinder

325/30R21 vs 285/30R22

285/30R22 is 0.06 in (1.4 mm) taller than 325/30R21, a +0.19% diameter difference. With the speedometer set for 325/30R21, an indicated 60 mph is 60.1 mph on 285/30R22.

Is this a safe swap?

Diameter difference +0.19%: under 1%

By overall diameter alone, 285/30R22 is a near match for 325/30R21; 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: 325/30R21 (28.68 in) vs 285/30R22 (28.73 in)325/30R2128.68 in × 12.80 in285/30R2228.73 in × 11.22 in
Side profile and tread width, drawn to the same scale.
325/30R21 vs 285/30R22 differences
Measurement325/30R21285/30R22Difference% diff
Overall diameter28.68 in (728.4 mm)28.73 in (729.8 mm)+0.06 in (+1.4 mm)+0.19%
Sidewall height3.84 in (97.5 mm)3.37 in (85.5 mm)−0.47 in (−12.0 mm)−12.31%
Section width12.80 in (325.0 mm)11.22 in (285.0 mm)−1.57 in (−40.0 mm)−12.31%
Circumference90.09 in (2,288.3 mm)90.27 in (2,292.7 mm)+0.17 in (+4.4 mm)+0.19%
Revolutions per mile703702−1−0.19%
True speed with the speedometer calibrated for 325/30R21
IndicatedActual on 325/30R21Actual on 285/30R22Difference
30 mph30.0 mph30.1 mph+0.1 mph
60 mph60.0 mph60.1 mph+0.1 mph
75 mph75.0 mph75.1 mph+0.1 mph

Ride-height change: 285/30R22 raises the vehicle by 0.03 in (0.7 mm) at the axle (half the +1.4 mm diameter difference).

285/30R22 is 0.06 in taller than 325/30R21 and 40 mm narrower, a 0.19% difference in overall diameter.

With the speedometer calibrated for 325/30R21, an indicated 60 mph is actually 60.1 mph on 285/30R22, and revolutions per mile change from 703 to 702.

285/30R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 325/30R21.

Size pages

Other comparisons with 325/30R21

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