TireSizesFinder

33x12.50R17 vs 315/70R17

315/70R17 is 1.36 in (34.6 mm) taller than 33x12.50R17, a +4.13% diameter difference. With the speedometer set for 33x12.50R17, an indicated 60 mph is 62.5 mph on 315/70R17.

Is this a safe swap?

Diameter difference +4.13%: outside the ±3% guideline

By overall diameter alone, 315/70R17 falls outside the ±3% range commonly used as a guideline when replacing 33x12.50R17; speedometer and ride-height changes are larger. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 33x12.50R17 (33.00 in) vs 315/70R17 (34.36 in)33x12.50R1733.00 in × 12.50 in315/70R1734.36 in × 12.40 in
Side profile and tread width, drawn to the same scale.
33x12.50R17 vs 315/70R17 differences
Measurement33x12.50R17315/70R17Difference% diff
Overall diameter33.00 in (838.2 mm)34.36 in (872.8 mm)+1.36 in (+34.6 mm)+4.13%
Sidewall height8.00 in (203.2 mm)8.68 in (220.5 mm)+0.68 in (+17.3 mm)+8.51%
Section width12.50 in (317.5 mm)12.40 in (315.0 mm)−0.10 in (−2.5 mm)−0.79%
Circumference103.67 in (2,633.3 mm)107.95 in (2,742.0 mm)+4.28 in (+108.7 mm)+4.13%
Revolutions per mile611587−24−3.96%
True speed with the speedometer calibrated for 33x12.50R17
IndicatedActual on 33x12.50R17Actual on 315/70R17Difference
30 mph30.0 mph31.2 mph+1.2 mph
60 mph60.0 mph62.5 mph+2.5 mph
75 mph75.0 mph78.1 mph+3.1 mph

Ride-height change: 315/70R17 raises the vehicle by 0.68 in (17.3 mm) at the axle (half the +34.6 mm diameter difference).

315/70R17 is 1.36 in taller than 33x12.50R17 and 3 mm narrower, a 4.13% difference in overall diameter.

With the speedometer calibrated for 33x12.50R17, an indicated 60 mph is actually 62.5 mph on 315/70R17, and revolutions per mile change from 611 to 587.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 33x12.50R17

Other comparisons with 315/70R17

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