315/35R20 vs 285/30R22

285/30R22 is 0.05 in (1.3 mm) taller than 315/35R20, a +0.18% diameter difference. With the speedometer set for 315/35R20, an indicated 60 mph is 60.1 mph on 285/30R22.

Is this a safe swap?

Diameter difference +0.18%: under 1%

By overall diameter alone, 285/30R22 is a near match for 315/35R20; the speedometer changes by less than 1%. 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.

315/35R20 vs 285/30R22 differences
Measurement	315/35R20	285/30R22	Difference	% diff
Overall diameter	28.68 in (728.5 mm)	28.73 in (729.8 mm)	+0.05 in (+1.3 mm)	+0.18%
Sidewall height	4.34 in (110.3 mm)	3.37 in (85.5 mm)	−0.97 in (−24.7 mm)	−22.45%
Section width	12.40 in (315.0 mm)	11.22 in (285.0 mm)	−1.18 in (−30.0 mm)	−9.52%
Circumference	90.10 in (2,288.7 mm)	90.27 in (2,292.7 mm)	+0.16 in (+4.1 mm)	+0.18%
Revolutions per mile	703	702	−1	−0.18%

True speed with the speedometer calibrated for 315/35R20
Indicated	Actual on 315/35R20	Actual on 285/30R22	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.1 mph	+0.1 mph
75 mph	75.0 mph	75.1 mph	+0.1 mph

Ride-height change: 285/30R22 raises the vehicle by 0.03 in (0.6 mm) at the axle (half the +1.3 mm diameter difference).

285/30R22 is 0.05 in taller than 315/35R20 and 30 mm narrower, a 0.18% difference in overall diameter.

With the speedometer calibrated for 315/35R20, 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-2 fitment from the 20-inch wheel of 315/35R20.

Size pages

Other comparisons with 315/35R20

Other comparisons with 285/30R22

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