TireSizesFinder

33x12.50R15 vs 255/85R16

255/85R16 is 0.07 in (1.7 mm) taller than 33x12.50R15, a +0.20% diameter difference. With the speedometer set for 33x12.50R15, 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 33x12.50R15; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 33x12.50R15 (33.00 in) vs 255/85R16 (33.07 in)33x12.50R1533.00 in × 12.50 in255/85R1633.07 in × 10.04 in
Side profile and tread width, drawn to the same scale.
33x12.50R15 vs 255/85R16 differences
Measurement33x12.50R15255/85R16Difference% diff
Overall diameter33.00 in (838.2 mm)33.07 in (839.9 mm)+0.07 in (+1.7 mm)+0.20%
Sidewall height9.00 in (228.6 mm)8.53 in (216.8 mm)−0.47 in (−11.8 mm)−5.18%
Section width12.50 in (317.5 mm)10.04 in (255.0 mm)−2.46 in (−62.5 mm)−19.69%
Circumference103.67 in (2,633.3 mm)103.88 in (2,638.6 mm)+0.21 in (+5.3 mm)+0.20%
Revolutions per mile611610−1−0.20%
True speed with the speedometer calibrated for 33x12.50R15
IndicatedActual on 33x12.50R15Actual on 255/85R16Difference
30 mph30.0 mph30.1 mph+0.1 mph
60 mph60.0 mph60.1 mph+0.1 mph
75 mph75.0 mph75.2 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 33x12.50R15 and 63 mm narrower, a 0.20% difference in overall diameter.

With the speedometer calibrated for 33x12.50R15, an indicated 60 mph is actually 60.1 mph on 255/85R16, and revolutions per mile change from 611 to 610.

255/85R16 mounts on a 16-inch wheel, a plus-1 fitment from the 15-inch wheel of 33x12.50R15.

Size pages

Other comparisons with 33x12.50R15

Other comparisons with 255/85R16

Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.