315/35R20 vs 245/35R22

245/35R22 is 0.07 in (1.8 mm) taller than 315/35R20, a +0.25% diameter difference. With the speedometer set for 315/35R20, an indicated 60 mph is 60.1 mph on 245/35R22.

Is this a safe swap?

Diameter difference +0.25%: under 1%

By overall diameter alone, 245/35R22 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 245/35R22 differences
Measurement	315/35R20	245/35R22	Difference	% diff
Overall diameter	28.68 in (728.5 mm)	28.75 in (730.3 mm)	+0.07 in (+1.8 mm)	+0.25%
Sidewall height	4.34 in (110.3 mm)	3.38 in (85.8 mm)	−0.96 in (−24.5 mm)	−22.22%
Section width	12.40 in (315.0 mm)	9.65 in (245.0 mm)	−2.76 in (−70.0 mm)	−22.22%
Circumference	90.10 in (2,288.7 mm)	90.33 in (2,294.3 mm)	+0.22 in (+5.7 mm)	+0.25%
Revolutions per mile	703	701	−2	−0.25%

True speed with the speedometer calibrated for 315/35R20
Indicated	Actual on 315/35R20	Actual on 245/35R22	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	75.2 mph	+0.2 mph

Ride-height change: 245/35R22 raises the vehicle by 0.04 in (0.9 mm) at the axle (half the +1.8 mm diameter difference).

245/35R22 is 0.07 in taller than 315/35R20 and 70 mm narrower, a 0.25% difference in overall diameter.

With the speedometer calibrated for 315/35R20, an indicated 60 mph is actually 60.1 mph on 245/35R22, and revolutions per mile change from 703 to 701.

245/35R22 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 245/35R22

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