33x12.50R15 vs 235/80R17

235/80R17 is 1.20 in (30.4 mm) shorter than 33x12.50R15, a −3.63% diameter difference. With the speedometer set for 33x12.50R15, an indicated 60 mph is 57.8 mph on 235/80R17.

Is this a safe swap?

Diameter difference −3.63%: outside the ±3% guideline

By overall diameter alone, 235/80R17 falls outside the ±3% range commonly used as a guideline when replacing 33x12.50R15; speedometer and ride-height changes are larger. 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.

33x12.50R15 vs 235/80R17 differences
Measurement	33x12.50R15	235/80R17	Difference	% diff
Overall diameter	33.00 in (838.2 mm)	31.80 in (807.8 mm)	−1.20 in (−30.4 mm)	−3.63%
Sidewall height	9.00 in (228.6 mm)	7.40 in (188.0 mm)	−1.60 in (−40.6 mm)	−17.76%
Section width	12.50 in (317.5 mm)	9.25 in (235.0 mm)	−3.25 in (−82.5 mm)	−25.98%
Circumference	103.67 in (2,633.3 mm)	99.91 in (2,537.8 mm)	−3.76 in (−95.5 mm)	−3.63%
Revolutions per mile	611	634	+23	+3.76%

True speed with the speedometer calibrated for 33x12.50R15
Indicated	Actual on 33x12.50R15	Actual on 235/80R17	Difference
30 mph	30.0 mph	28.9 mph	−1.1 mph
60 mph	60.0 mph	57.8 mph	−2.2 mph
75 mph	75.0 mph	72.3 mph	−2.7 mph

Ride-height change: 235/80R17 lowers the vehicle by 0.60 in (15.2 mm) at the axle (half the −30.4 mm diameter difference).

235/80R17 is 1.20 in shorter than 33x12.50R15 and 83 mm narrower, a 3.63% difference in overall diameter.

With the speedometer calibrated for 33x12.50R15, an indicated 60 mph is actually 57.8 mph on 235/80R17, and revolutions per mile change from 611 to 634.

235/80R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 33x12.50R15.

Size pages

Other comparisons with 33x12.50R15

Other comparisons with 235/80R17

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