31x10.50R16 vs 285/60R18

285/60R18 is 0.46 in (11.8 mm) taller than 31x10.50R16, a +1.50% diameter difference. With the speedometer set for 31x10.50R16, an indicated 60 mph is 60.9 mph on 285/60R18.

Is this a safe swap?

Diameter difference +1.50%: within the ±3% guideline

By overall diameter alone, 285/60R18 falls inside the ±3% range commonly used as a guideline when replacing 31x10.50R16. 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.

31x10.50R16 vs 285/60R18 differences
Measurement	31x10.50R16	285/60R18	Difference	% diff
Overall diameter	31.00 in (787.4 mm)	31.46 in (799.2 mm)	+0.46 in (+11.8 mm)	+1.50%
Sidewall height	7.50 in (190.5 mm)	6.73 in (171.0 mm)	−0.77 in (−19.5 mm)	−10.24%
Section width	10.50 in (266.7 mm)	11.22 in (285.0 mm)	+0.72 in (+18.3 mm)	+6.86%
Circumference	97.39 in (2,473.7 mm)	98.85 in (2,510.8 mm)	+1.46 in (+37.1 mm)	+1.50%
Revolutions per mile	651	641	−10	−1.48%

True speed with the speedometer calibrated for 31x10.50R16
Indicated	Actual on 31x10.50R16	Actual on 285/60R18	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.9 mph	+0.9 mph
75 mph	75.0 mph	76.1 mph	+1.1 mph

Ride-height change: 285/60R18 raises the vehicle by 0.23 in (5.9 mm) at the axle (half the +11.8 mm diameter difference).

285/60R18 is 0.46 in taller than 31x10.50R16 and 18 mm wider, a 1.50% difference in overall diameter.

With the speedometer calibrated for 31x10.50R16, an indicated 60 mph is actually 60.9 mph on 285/60R18, and revolutions per mile change from 651 to 641.

285/60R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 31x10.50R16.

Size pages

Other comparisons with 31x10.50R16

Other comparisons with 285/60R18

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