285/75R16 vs 33x12.50R18

33x12.50R18 is 0.17 in (4.3 mm) taller than 285/75R16, a +0.52% diameter difference. With the speedometer set for 285/75R16, an indicated 60 mph is 60.3 mph on 33x12.50R18.

Is this a safe swap?

Diameter difference +0.52%: under 1%

By overall diameter alone, 33x12.50R18 is a near match for 285/75R16; 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.

285/75R16 vs 33x12.50R18 differences
Measurement	285/75R16	33x12.50R18	Difference	% diff
Overall diameter	32.83 in (833.9 mm)	33.00 in (838.2 mm)	+0.17 in (+4.3 mm)	+0.52%
Sidewall height	8.42 in (213.8 mm)	7.50 in (190.5 mm)	−0.92 in (−23.2 mm)	−10.88%
Section width	11.22 in (285.0 mm)	12.50 in (317.5 mm)	+1.28 in (+32.5 mm)	+11.40%
Circumference	103.14 in (2,619.8 mm)	103.67 in (2,633.3 mm)	+0.53 in (+13.5 mm)	+0.52%
Revolutions per mile	614	611	−3	−0.51%

True speed with the speedometer calibrated for 285/75R16
Indicated	Actual on 285/75R16	Actual on 33x12.50R18	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.3 mph	+0.3 mph
75 mph	75.0 mph	75.4 mph	+0.4 mph

Ride-height change: 33x12.50R18 raises the vehicle by 0.08 in (2.2 mm) at the axle (half the +4.3 mm diameter difference).

33x12.50R18 is 0.17 in taller than 285/75R16 and 33 mm wider, a 0.52% difference in overall diameter.

With the speedometer calibrated for 285/75R16, an indicated 60 mph is actually 60.3 mph on 33x12.50R18, and revolutions per mile change from 614 to 611.

33x12.50R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 285/75R16.

Size pages

Other comparisons with 285/75R16

Other comparisons with 33x12.50R18

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