285/75R17 vs 315/70R17

315/70R17 is 0.53 in (13.5 mm) taller than 285/75R17, a +1.57% diameter difference. With the speedometer set for 285/75R17, an indicated 60 mph is 60.9 mph on 315/70R17.

Is this a safe swap?

Diameter difference +1.57%: within the ±3% guideline

By overall diameter alone, 315/70R17 falls inside the ±3% range commonly used as a guideline when replacing 285/75R17. 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.

285/75R17 vs 315/70R17 differences
Measurement	285/75R17	315/70R17	Difference	% diff
Overall diameter	33.83 in (859.3 mm)	34.36 in (872.8 mm)	+0.53 in (+13.5 mm)	+1.57%
Sidewall height	8.42 in (213.8 mm)	8.68 in (220.5 mm)	+0.27 in (+6.8 mm)	+3.16%
Section width	11.22 in (285.0 mm)	12.40 in (315.0 mm)	+1.18 in (+30.0 mm)	+10.53%
Circumference	106.28 in (2,699.6 mm)	107.95 in (2,742.0 mm)	+1.67 in (+42.4 mm)	+1.57%
Revolutions per mile	596	587	−9	−1.55%

True speed with the speedometer calibrated for 285/75R17
Indicated	Actual on 285/75R17	Actual on 315/70R17	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	60.9 mph	+0.9 mph
75 mph	75.0 mph	76.2 mph	+1.2 mph

Ride-height change: 315/70R17 raises the vehicle by 0.27 in (6.8 mm) at the axle (half the +13.5 mm diameter difference).

315/70R17 is 0.53 in taller than 285/75R17 and 30 mm wider, a 1.57% difference in overall diameter.

With the speedometer calibrated for 285/75R17, an indicated 60 mph is actually 60.9 mph on 315/70R17, and revolutions per mile change from 596 to 587.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 285/75R17

Other comparisons with 315/70R17

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