TireSizesFinder

31x10.50R15 vs 245/70R17

245/70R17 is 0.50 in (12.6 mm) shorter than 31x10.50R15, a −1.60% diameter difference. With the speedometer set for 31x10.50R15, an indicated 60 mph is 59.0 mph on 245/70R17.

Is this a safe swap?

Diameter difference −1.60%: within the ±3% guideline

By overall diameter alone, 245/70R17 falls inside the ±3% range commonly used as a guideline when replacing 31x10.50R15. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 31x10.50R15 (31.00 in) vs 245/70R17 (30.50 in)31x10.50R1531.00 in × 10.50 in245/70R1730.50 in × 9.65 in
Side profile and tread width, drawn to the same scale.
31x10.50R15 vs 245/70R17 differences
Measurement31x10.50R15245/70R17Difference% diff
Overall diameter31.00 in (787.4 mm)30.50 in (774.8 mm)−0.50 in (−12.6 mm)−1.60%
Sidewall height8.00 in (203.2 mm)6.75 in (171.5 mm)−1.25 in (−31.7 mm)−15.60%
Section width10.50 in (266.7 mm)9.65 in (245.0 mm)−0.85 in (−21.7 mm)−8.14%
Circumference97.39 in (2,473.7 mm)95.83 in (2,434.1 mm)−1.56 in (−39.6 mm)−1.60%
Revolutions per mile651661+11+1.63%
True speed with the speedometer calibrated for 31x10.50R15
IndicatedActual on 31x10.50R15Actual on 245/70R17Difference
30 mph30.0 mph29.5 mph−0.5 mph
60 mph60.0 mph59.0 mph−1.0 mph
75 mph75.0 mph73.8 mph−1.2 mph

Ride-height change: 245/70R17 lowers the vehicle by 0.25 in (6.3 mm) at the axle (half the −12.6 mm diameter difference).

245/70R17 is 0.50 in shorter than 31x10.50R15 and 22 mm narrower, a 1.60% difference in overall diameter.

With the speedometer calibrated for 31x10.50R15, an indicated 60 mph is actually 59.0 mph on 245/70R17, and revolutions per mile change from 651 to 661.

245/70R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 31x10.50R15.

Size pages

Other comparisons with 31x10.50R15

Other comparisons with 245/70R17

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