245/50R20 vs 265/50R20

265/50R20 is 0.79 in (20.0 mm) taller than 245/50R20, a +2.66% diameter difference. With the speedometer set for 245/50R20, an indicated 60 mph is 61.6 mph on 265/50R20.

Is this a safe swap?

Diameter difference +2.66%: within the ±3% guideline

By overall diameter alone, 265/50R20 falls inside the ±3% range commonly used as a guideline when replacing 245/50R20. 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.

245/50R20 vs 265/50R20 differences
Measurement	245/50R20	265/50R20	Difference	% diff
Overall diameter	29.65 in (753.0 mm)	30.43 in (773.0 mm)	+0.79 in (+20.0 mm)	+2.66%
Sidewall height	4.82 in (122.5 mm)	5.22 in (132.5 mm)	+0.39 in (+10.0 mm)	+8.16%
Section width	9.65 in (245.0 mm)	10.43 in (265.0 mm)	+0.79 in (+20.0 mm)	+8.16%
Circumference	93.13 in (2,365.6 mm)	95.61 in (2,428.5 mm)	+2.47 in (+62.8 mm)	+2.66%
Revolutions per mile	680	663	−18	−2.59%

True speed with the speedometer calibrated for 245/50R20
Indicated	Actual on 245/50R20	Actual on 265/50R20	Difference
30 mph	30.0 mph	30.8 mph	+0.8 mph
60 mph	60.0 mph	61.6 mph	+1.6 mph
75 mph	75.0 mph	77.0 mph	+2.0 mph

Ride-height change: 265/50R20 raises the vehicle by 0.39 in (10.0 mm) at the axle (half the +20.0 mm diameter difference).

265/50R20 is 0.79 in taller than 245/50R20 and 20 mm wider, a 2.66% difference in overall diameter.

With the speedometer calibrated for 245/50R20, an indicated 60 mph is actually 61.6 mph on 265/50R20, and revolutions per mile change from 680 to 663.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 245/50R20

Other comparisons with 265/50R20

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