265/70R15 vs 31x10.50R15

31x10.50R15 is 1.39 in (35.4 mm) taller than 265/70R15, a +4.71% diameter difference. With the speedometer set for 265/70R15, an indicated 60 mph is 62.8 mph on 31x10.50R15.

Is this a safe swap?

Diameter difference +4.71%: outside the ±3% guideline

By overall diameter alone, 31x10.50R15 falls outside the ±3% range commonly used as a guideline when replacing 265/70R15; 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.

265/70R15 vs 31x10.50R15 differences
Measurement	265/70R15	31x10.50R15	Difference	% diff
Overall diameter	29.61 in (752.0 mm)	31.00 in (787.4 mm)	+1.39 in (+35.4 mm)	+4.71%
Sidewall height	7.30 in (185.5 mm)	8.00 in (203.2 mm)	+0.70 in (+17.7 mm)	+9.54%
Section width	10.43 in (265.0 mm)	10.50 in (266.7 mm)	+0.07 in (+1.7 mm)	+0.64%
Circumference	93.01 in (2,362.5 mm)	97.39 in (2,473.7 mm)	+4.38 in (+111.2 mm)	+4.71%
Revolutions per mile	681	651	−31	−4.50%

True speed with the speedometer calibrated for 265/70R15
Indicated	Actual on 265/70R15	Actual on 31x10.50R15	Difference
30 mph	30.0 mph	31.4 mph	+1.4 mph
60 mph	60.0 mph	62.8 mph	+2.8 mph
75 mph	75.0 mph	78.5 mph	+3.5 mph

Ride-height change: 31x10.50R15 raises the vehicle by 0.70 in (17.7 mm) at the axle (half the +35.4 mm diameter difference).

31x10.50R15 is 1.39 in taller than 265/70R15 and 2 mm wider, a 4.71% difference in overall diameter.

With the speedometer calibrated for 265/70R15, an indicated 60 mph is actually 62.8 mph on 31x10.50R15, and revolutions per mile change from 681 to 651.

Both sizes mount on 15-inch wheels.

Size pages

Other comparisons with 265/70R15

Other comparisons with 31x10.50R15

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