265/75R15 vs 31x10.50R15

31x10.50R15 is 0.35 in (8.9 mm) taller than 265/75R15, a +1.14% diameter difference. With the speedometer set for 265/75R15, an indicated 60 mph is 60.7 mph on 31x10.50R15.

Is this a safe swap?

Diameter difference +1.14%: within the ±3% guideline

By overall diameter alone, 31x10.50R15 falls inside the ±3% range commonly used as a guideline when replacing 265/75R15. 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.

265/75R15 vs 31x10.50R15 differences
Measurement	265/75R15	31x10.50R15	Difference	% diff
Overall diameter	30.65 in (778.5 mm)	31.00 in (787.4 mm)	+0.35 in (+8.9 mm)	+1.14%
Sidewall height	7.82 in (198.8 mm)	8.00 in (203.2 mm)	+0.18 in (+4.4 mm)	+2.24%
Section width	10.43 in (265.0 mm)	10.50 in (266.7 mm)	+0.07 in (+1.7 mm)	+0.64%
Circumference	96.29 in (2,445.7 mm)	97.39 in (2,473.7 mm)	+1.10 in (+28.0 mm)	+1.14%
Revolutions per mile	658	651	−7	−1.13%

True speed with the speedometer calibrated for 265/75R15
Indicated	Actual on 265/75R15	Actual on 31x10.50R15	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.7 mph	+0.7 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 31x10.50R15 raises the vehicle by 0.18 in (4.4 mm) at the axle (half the +8.9 mm diameter difference).

31x10.50R15 is 0.35 in taller than 265/75R15 and 2 mm wider, a 1.14% difference in overall diameter.

With the speedometer calibrated for 265/75R15, an indicated 60 mph is actually 60.7 mph on 31x10.50R15, and revolutions per mile change from 658 to 651.

Both sizes mount on 15-inch wheels.

Size pages

Other comparisons with 265/75R15

Other comparisons with 31x10.50R15

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