285/55R20 vs 325/45R22

325/45R22 is 1.17 in (29.8 mm) taller than 285/55R20, a +3.63% diameter difference. With the speedometer set for 285/55R20, an indicated 60 mph is 62.2 mph on 325/45R22.

Is this a safe swap?

Diameter difference +3.63%: outside the ±3% guideline

By overall diameter alone, 325/45R22 falls outside the ±3% range commonly used as a guideline when replacing 285/55R20; speedometer and ride-height changes are larger. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

285/55R20 vs 325/45R22 differences
Measurement	285/55R20	325/45R22	Difference	% diff
Overall diameter	32.34 in (821.5 mm)	33.52 in (851.3 mm)	+1.17 in (+29.8 mm)	+3.63%
Sidewall height	6.17 in (156.8 mm)	5.76 in (146.3 mm)	−0.41 in (−10.5 mm)	−6.70%
Section width	11.22 in (285.0 mm)	12.80 in (325.0 mm)	+1.57 in (+40.0 mm)	+14.04%
Circumference	101.61 in (2,580.8 mm)	105.29 in (2,674.4 mm)	+3.69 in (+93.6 mm)	+3.63%
Revolutions per mile	624	602	−22	−3.50%

True speed with the speedometer calibrated for 285/55R20
Indicated	Actual on 285/55R20	Actual on 325/45R22	Difference
30 mph	30.0 mph	31.1 mph	+1.1 mph
60 mph	60.0 mph	62.2 mph	+2.2 mph
75 mph	75.0 mph	77.7 mph	+2.7 mph

Ride-height change: 325/45R22 raises the vehicle by 0.59 in (14.9 mm) at the axle (half the +29.8 mm diameter difference).

325/45R22 is 1.17 in taller than 285/55R20 and 40 mm wider, a 3.63% difference in overall diameter.

With the speedometer calibrated for 285/55R20, an indicated 60 mph is actually 62.2 mph on 325/45R22, and revolutions per mile change from 624 to 602.

325/45R22 mounts on a 22-inch wheel, a plus-2 fitment from the 20-inch wheel of 285/55R20.

Size pages

Other comparisons with 285/55R20

Other comparisons with 325/45R22

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.