245/50R20 vs 315/30R22

315/30R22 is 0.20 in (5.2 mm) shorter than 245/50R20, a −0.69% diameter difference. With the speedometer set for 245/50R20, an indicated 60 mph is 59.6 mph on 315/30R22.

Is this a safe swap?

Diameter difference −0.69%: under 1%

By overall diameter alone, 315/30R22 is a near match for 245/50R20; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

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

245/50R20 vs 315/30R22 differences
Measurement	245/50R20	315/30R22	Difference	% diff
Overall diameter	29.65 in (753.0 mm)	29.44 in (747.8 mm)	−0.20 in (−5.2 mm)	−0.69%
Sidewall height	4.82 in (122.5 mm)	3.72 in (94.5 mm)	−1.10 in (−28.0 mm)	−22.86%
Section width	9.65 in (245.0 mm)	12.40 in (315.0 mm)	+2.76 in (+70.0 mm)	+28.57%
Circumference	93.13 in (2,365.6 mm)	92.49 in (2,349.3 mm)	−0.64 in (−16.3 mm)	−0.69%
Revolutions per mile	680	685	+5	+0.70%

True speed with the speedometer calibrated for 245/50R20
Indicated	Actual on 245/50R20	Actual on 315/30R22	Difference
30 mph	30.0 mph	29.8 mph	−0.2 mph
60 mph	60.0 mph	59.6 mph	−0.4 mph
75 mph	75.0 mph	74.5 mph	−0.5 mph

Ride-height change: 315/30R22 lowers the vehicle by 0.10 in (2.6 mm) at the axle (half the −5.2 mm diameter difference).

315/30R22 is 0.20 in shorter than 245/50R20 and 70 mm wider, a 0.69% difference in overall diameter.

With the speedometer calibrated for 245/50R20, an indicated 60 mph is actually 59.6 mph on 315/30R22, and revolutions per mile change from 680 to 685.

315/30R22 mounts on a 22-inch wheel, a plus-2 fitment from the 20-inch wheel of 245/50R20.

Size pages

Other comparisons with 245/50R20

Other comparisons with 315/30R22

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