215/85R16 vs 31x10.50R16

31x10.50R16 is 0.61 in (15.5 mm) taller than 215/85R16, a +2.01% diameter difference. With the speedometer set for 215/85R16, an indicated 60 mph is 61.2 mph on 31x10.50R16.

Is this a safe swap?

Diameter difference +2.01%: within the ±3% guideline

By overall diameter alone, 31x10.50R16 falls inside the ±3% range commonly used as a guideline when replacing 215/85R16. 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.

215/85R16 vs 31x10.50R16 differences
Measurement	215/85R16	31x10.50R16	Difference	% diff
Overall diameter	30.39 in (771.9 mm)	31.00 in (787.4 mm)	+0.61 in (+15.5 mm)	+2.01%
Sidewall height	7.19 in (182.8 mm)	7.50 in (190.5 mm)	+0.31 in (+7.8 mm)	+4.24%
Section width	8.46 in (215.0 mm)	10.50 in (266.7 mm)	+2.04 in (+51.7 mm)	+24.05%
Circumference	95.47 in (2,425.0 mm)	97.39 in (2,473.7 mm)	+1.92 in (+48.7 mm)	+2.01%
Revolutions per mile	664	651	−13	−1.97%

True speed with the speedometer calibrated for 215/85R16
Indicated	Actual on 215/85R16	Actual on 31x10.50R16	Difference
30 mph	30.0 mph	30.6 mph	+0.6 mph
60 mph	60.0 mph	61.2 mph	+1.2 mph
75 mph	75.0 mph	76.5 mph	+1.5 mph

Ride-height change: 31x10.50R16 raises the vehicle by 0.31 in (7.8 mm) at the axle (half the +15.5 mm diameter difference).

31x10.50R16 is 0.61 in taller than 215/85R16 and 52 mm wider, a 2.01% difference in overall diameter.

With the speedometer calibrated for 215/85R16, an indicated 60 mph is actually 61.2 mph on 31x10.50R16, and revolutions per mile change from 664 to 651.

Both sizes mount on 16-inch wheels.

Size pages

Other comparisons with 215/85R16

Other comparisons with 31x10.50R16

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