275/45R20 vs 315/30R22

315/30R22 is 0.30 in (7.7 mm) shorter than 275/45R20, a −1.02% diameter difference. With the speedometer set for 275/45R20, an indicated 60 mph is 59.4 mph on 315/30R22.

Is this a safe swap?

Diameter difference −1.02%: within the ±3% guideline

By overall diameter alone, 315/30R22 falls inside the ±3% range commonly used as a guideline when replacing 275/45R20. 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.

275/45R20 vs 315/30R22 differences
Measurement	275/45R20	315/30R22	Difference	% diff
Overall diameter	29.74 in (755.5 mm)	29.44 in (747.8 mm)	−0.30 in (−7.7 mm)	−1.02%
Sidewall height	4.87 in (123.8 mm)	3.72 in (94.5 mm)	−1.15 in (−29.2 mm)	−23.64%
Section width	10.83 in (275.0 mm)	12.40 in (315.0 mm)	+1.57 in (+40.0 mm)	+14.55%
Circumference	93.44 in (2,373.5 mm)	92.49 in (2,349.3 mm)	−0.95 in (−24.2 mm)	−1.02%
Revolutions per mile	678	685	+7	+1.03%

True speed with the speedometer calibrated for 275/45R20
Indicated	Actual on 275/45R20	Actual on 315/30R22	Difference
30 mph	30.0 mph	29.7 mph	−0.3 mph
60 mph	60.0 mph	59.4 mph	−0.6 mph
75 mph	75.0 mph	74.2 mph	−0.8 mph

Ride-height change: 315/30R22 lowers the vehicle by 0.15 in (3.9 mm) at the axle (half the −7.7 mm diameter difference).

315/30R22 is 0.30 in shorter than 275/45R20 and 40 mm wider, a 1.02% difference in overall diameter.

With the speedometer calibrated for 275/45R20, an indicated 60 mph is actually 59.4 mph on 315/30R22, and revolutions per mile change from 678 to 685.

315/30R22 mounts on a 22-inch wheel, a plus-2 fitment from the 20-inch wheel of 275/45R20.

Size pages

Other comparisons with 275/45R20

Other comparisons with 315/30R22

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