33x12.50R17 vs 255/80R17

255/80R17 is 0.06 in (1.6 mm) taller than 33x12.50R17, a +0.19% diameter difference. With the speedometer set for 33x12.50R17, an indicated 60 mph is 60.1 mph on 255/80R17.

Is this a safe swap?

Diameter difference +0.19%: under 1%

By overall diameter alone, 255/80R17 is a near match for 33x12.50R17; 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.

33x12.50R17 vs 255/80R17 differences
Measurement	33x12.50R17	255/80R17	Difference	% diff
Overall diameter	33.00 in (838.2 mm)	33.06 in (839.8 mm)	+0.06 in (+1.6 mm)	+0.19%
Sidewall height	8.00 in (203.2 mm)	8.03 in (204.0 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)	103.87 in (2,638.3 mm)	+0.20 in (+5.0 mm)	+0.19%
Revolutions per mile	611	610	−1	−0.19%

True speed with the speedometer calibrated for 33x12.50R17
Indicated	Actual on 33x12.50R17	Actual on 255/80R17	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	75.1 mph	+0.1 mph

Ride-height change: 255/80R17 raises the vehicle by 0.03 in (0.8 mm) at the axle (half the +1.6 mm diameter difference).

255/80R17 is 0.06 in taller than 33x12.50R17 and 63 mm narrower, a 0.19% difference in overall diameter.

With the speedometer calibrated for 33x12.50R17, an indicated 60 mph is actually 60.1 mph on 255/80R17, and revolutions per mile change from 611 to 610.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 33x12.50R17

Other comparisons with 255/80R17

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