33x12.50R16 vs 255/85R16

255/85R16 is 0.07 in (1.7 mm) taller than 33x12.50R16, a +0.20% diameter difference. With the speedometer set for 33x12.50R16, an indicated 60 mph is 60.1 mph on 255/85R16.

Is this a safe swap?

Diameter difference +0.20%: under 1%

By overall diameter alone, 255/85R16 is a near match for 33x12.50R16; 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.

33x12.50R16 vs 255/85R16 differences
Measurement	33x12.50R16	255/85R16	Difference	% diff
Overall diameter	33.00 in (838.2 mm)	33.07 in (839.9 mm)	+0.07 in (+1.7 mm)	+0.20%
Sidewall height	8.50 in (215.9 mm)	8.53 in (216.8 mm)	+0.03 in (+0.8 mm)	+0.39%
Section width	12.50 in (317.5 mm)	10.04 in (255.0 mm)	−2.46 in (−62.5 mm)	−19.69%
Circumference	103.67 in (2,633.3 mm)	103.88 in (2,638.6 mm)	+0.21 in (+5.3 mm)	+0.20%
Revolutions per mile	611	610	−1	−0.20%

True speed with the speedometer calibrated for 33x12.50R16
Indicated	Actual on 33x12.50R16	Actual on 255/85R16	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.1 mph	+0.1 mph
75 mph	75.0 mph	75.2 mph	+0.2 mph

Ride-height change: 255/85R16 raises the vehicle by 0.03 in (0.8 mm) at the axle (half the +1.7 mm diameter difference).

255/85R16 is 0.07 in taller than 33x12.50R16 and 63 mm narrower, a 0.20% difference in overall diameter.

With the speedometer calibrated for 33x12.50R16, an indicated 60 mph is actually 60.1 mph on 255/85R16, and revolutions per mile change from 611 to 610.

Both sizes mount on 16-inch wheels.

Size pages

Other comparisons with 33x12.50R16

Other comparisons with 255/85R16

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