32x11.50R15 vs 33x12.50R15

33x12.50R15 is 1.00 in (25.4 mm) taller than 32x11.50R15, a +3.13% diameter difference. With the speedometer set for 32x11.50R15, an indicated 60 mph is 61.9 mph on 33x12.50R15.

Is this a safe swap?

Diameter difference +3.13%: outside the ±3% guideline

By overall diameter alone, 33x12.50R15 falls outside the ±3% range commonly used as a guideline when replacing 32x11.50R15; 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.

32x11.50R15 vs 33x12.50R15 differences
Measurement	32x11.50R15	33x12.50R15	Difference	% diff
Overall diameter	32.00 in (812.8 mm)	33.00 in (838.2 mm)	+1.00 in (+25.4 mm)	+3.13%
Sidewall height	8.50 in (215.9 mm)	9.00 in (228.6 mm)	+0.50 in (+12.7 mm)	+5.88%
Section width	11.50 in (292.1 mm)	12.50 in (317.5 mm)	+1.00 in (+25.4 mm)	+8.70%
Circumference	100.53 in (2,553.5 mm)	103.67 in (2,633.3 mm)	+3.14 in (+79.8 mm)	+3.13%
Revolutions per mile	630	611	−19	−3.03%

True speed with the speedometer calibrated for 32x11.50R15
Indicated	Actual on 32x11.50R15	Actual on 33x12.50R15	Difference
30 mph	30.0 mph	30.9 mph	+0.9 mph
60 mph	60.0 mph	61.9 mph	+1.9 mph
75 mph	75.0 mph	77.3 mph	+2.3 mph

Ride-height change: 33x12.50R15 raises the vehicle by 0.50 in (12.7 mm) at the axle (half the +25.4 mm diameter difference).

33x12.50R15 is 1.00 in taller than 32x11.50R15 and 25 mm wider, a 3.13% difference in overall diameter.

With the speedometer calibrated for 32x11.50R15, an indicated 60 mph is actually 61.9 mph on 33x12.50R15, and revolutions per mile change from 630 to 611.

Both sizes mount on 15-inch wheels.

Size pages

Other comparisons with 32x11.50R15

Other comparisons with 33x12.50R15

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