TireSizesFinder

31x10.50R16 vs 245/65R18

245/65R18 is 0.46 in (11.7 mm) shorter than 31x10.50R16, a −1.49% diameter difference. With the speedometer set for 31x10.50R16, an indicated 60 mph is 59.1 mph on 245/65R18.

Is this a safe swap?

Diameter difference −1.49%: within the ±3% guideline

By overall diameter alone, 245/65R18 falls inside the ±3% range commonly used as a guideline when replacing 31x10.50R16. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 31x10.50R16 (31.00 in) vs 245/65R18 (30.54 in)31x10.50R1631.00 in × 10.50 in245/65R1830.54 in × 9.65 in
Side profile and tread width, drawn to the same scale.
31x10.50R16 vs 245/65R18 differences
Measurement31x10.50R16245/65R18Difference% diff
Overall diameter31.00 in (787.4 mm)30.54 in (775.7 mm)−0.46 in (−11.7 mm)−1.49%
Sidewall height7.50 in (190.5 mm)6.27 in (159.3 mm)−1.23 in (−31.2 mm)−16.40%
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)95.94 in (2,436.9 mm)−1.45 in (−36.8 mm)−1.49%
Revolutions per mile651660+10+1.51%
True speed with the speedometer calibrated for 31x10.50R16
IndicatedActual on 31x10.50R16Actual on 245/65R18Difference
30 mph30.0 mph29.6 mph−0.4 mph
60 mph60.0 mph59.1 mph−0.9 mph
75 mph75.0 mph73.9 mph−1.1 mph

Ride-height change: 245/65R18 lowers the vehicle by 0.23 in (5.8 mm) at the axle (half the −11.7 mm diameter difference).

245/65R18 is 0.46 in shorter than 31x10.50R16 and 22 mm narrower, a 1.49% difference in overall diameter.

With the speedometer calibrated for 31x10.50R16, an indicated 60 mph is actually 59.1 mph on 245/65R18, and revolutions per mile change from 651 to 660.

245/65R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 31x10.50R16.

Size pages

Other comparisons with 31x10.50R16

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