275/65R20 vs 315/60R20

315/60R20 is 0.81 in (20.5 mm) taller than 275/65R20, a +2.37% diameter difference. With the speedometer set for 275/65R20, an indicated 60 mph is 61.4 mph on 315/60R20.

Is this a safe swap?

Diameter difference +2.37%: within the ±3% guideline

By overall diameter alone, 315/60R20 falls inside the ±3% range commonly used as a guideline when replacing 275/65R20. 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.

275/65R20 vs 315/60R20 differences
Measurement	275/65R20	315/60R20	Difference	% diff
Overall diameter	34.07 in (865.5 mm)	34.88 in (886.0 mm)	+0.81 in (+20.5 mm)	+2.37%
Sidewall height	7.04 in (178.8 mm)	7.44 in (189.0 mm)	+0.40 in (+10.3 mm)	+5.73%
Section width	10.83 in (275.0 mm)	12.40 in (315.0 mm)	+1.57 in (+40.0 mm)	+14.55%
Circumference	107.05 in (2,719.0 mm)	109.58 in (2,783.5 mm)	+2.54 in (+64.4 mm)	+2.37%
Revolutions per mile	592	578	−14	−2.31%

True speed with the speedometer calibrated for 275/65R20
Indicated	Actual on 275/65R20	Actual on 315/60R20	Difference
30 mph	30.0 mph	30.7 mph	+0.7 mph
60 mph	60.0 mph	61.4 mph	+1.4 mph
75 mph	75.0 mph	76.8 mph	+1.8 mph

Ride-height change: 315/60R20 raises the vehicle by 0.40 in (10.3 mm) at the axle (half the +20.5 mm diameter difference).

315/60R20 is 0.81 in taller than 275/65R20 and 40 mm wider, a 2.37% difference in overall diameter.

With the speedometer calibrated for 275/65R20, an indicated 60 mph is actually 61.4 mph on 315/60R20, and revolutions per mile change from 592 to 578.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 275/65R20

Other comparisons with 315/60R20

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