265/45R20 vs 245/50R20

245/50R20 is 0.26 in (6.5 mm) taller than 265/45R20, a +0.87% diameter difference. With the speedometer set for 265/45R20, an indicated 60 mph is 60.5 mph on 245/50R20.

Is this a safe swap?

Diameter difference +0.87%: under 1%

By overall diameter alone, 245/50R20 is a near match for 265/45R20; the speedometer changes by less than 1%. 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.

265/45R20 vs 245/50R20 differences
Measurement	265/45R20	245/50R20	Difference	% diff
Overall diameter	29.39 in (746.5 mm)	29.65 in (753.0 mm)	+0.26 in (+6.5 mm)	+0.87%
Sidewall height	4.69 in (119.3 mm)	4.82 in (122.5 mm)	+0.13 in (+3.3 mm)	+2.73%
Section width	10.43 in (265.0 mm)	9.65 in (245.0 mm)	−0.79 in (−20.0 mm)	−7.55%
Circumference	92.33 in (2,345.2 mm)	93.13 in (2,365.6 mm)	+0.80 in (+20.4 mm)	+0.87%
Revolutions per mile	686	680	−6	−0.86%

True speed with the speedometer calibrated for 265/45R20
Indicated	Actual on 265/45R20	Actual on 245/50R20	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.5 mph	+0.5 mph
75 mph	75.0 mph	75.7 mph	+0.7 mph

Ride-height change: 245/50R20 raises the vehicle by 0.13 in (3.3 mm) at the axle (half the +6.5 mm diameter difference).

245/50R20 is 0.26 in taller than 265/45R20 and 20 mm narrower, a 0.87% difference in overall diameter.

With the speedometer calibrated for 265/45R20, an indicated 60 mph is actually 60.5 mph on 245/50R20, and revolutions per mile change from 686 to 680.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 265/45R20

Other comparisons with 245/50R20

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