33x12.50R18 vs 295/70R18

295/70R18 is 1.26 in (32.0 mm) taller than 33x12.50R18, a +3.82% diameter difference. With the speedometer set for 33x12.50R18, an indicated 60 mph is 62.3 mph on 295/70R18.

Is this a safe swap?

Diameter difference +3.82%: outside the ±3% guideline

By overall diameter alone, 295/70R18 falls outside the ±3% range commonly used as a guideline when replacing 33x12.50R18; 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.

33x12.50R18 vs 295/70R18 differences
Measurement	33x12.50R18	295/70R18	Difference	% diff
Overall diameter	33.00 in (838.2 mm)	34.26 in (870.2 mm)	+1.26 in (+32.0 mm)	+3.82%
Sidewall height	7.50 in (190.5 mm)	8.13 in (206.5 mm)	+0.63 in (+16.0 mm)	+8.40%
Section width	12.50 in (317.5 mm)	11.61 in (295.0 mm)	−0.89 in (−22.5 mm)	−7.09%
Circumference	103.67 in (2,633.3 mm)	107.63 in (2,733.8 mm)	+3.96 in (+100.5 mm)	+3.82%
Revolutions per mile	611	589	−22	−3.68%

True speed with the speedometer calibrated for 33x12.50R18
Indicated	Actual on 33x12.50R18	Actual on 295/70R18	Difference
30 mph	30.0 mph	31.1 mph	+1.1 mph
60 mph	60.0 mph	62.3 mph	+2.3 mph
75 mph	75.0 mph	77.9 mph	+2.9 mph

Ride-height change: 295/70R18 raises the vehicle by 0.63 in (16.0 mm) at the axle (half the +32.0 mm diameter difference).

295/70R18 is 1.26 in taller than 33x12.50R18 and 23 mm narrower, a 3.82% difference in overall diameter.

With the speedometer calibrated for 33x12.50R18, an indicated 60 mph is actually 62.3 mph on 295/70R18, and revolutions per mile change from 611 to 589.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 33x12.50R18

Other comparisons with 295/70R18

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