285/45R20 vs 265/50R20

265/50R20 is 0.33 in (8.5 mm) taller than 285/45R20, a +1.11% diameter difference. With the speedometer set for 285/45R20, an indicated 60 mph is 60.7 mph on 265/50R20.

Is this a safe swap?

Diameter difference +1.11%: within the ±3% guideline

By overall diameter alone, 265/50R20 falls inside the ±3% range commonly used as a guideline when replacing 285/45R20. 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.

285/45R20 vs 265/50R20 differences
Measurement	285/45R20	265/50R20	Difference	% diff
Overall diameter	30.10 in (764.5 mm)	30.43 in (773.0 mm)	+0.33 in (+8.5 mm)	+1.11%
Sidewall height	5.05 in (128.3 mm)	5.22 in (132.5 mm)	+0.17 in (+4.3 mm)	+3.31%
Section width	11.22 in (285.0 mm)	10.43 in (265.0 mm)	−0.79 in (−20.0 mm)	−7.02%
Circumference	94.56 in (2,401.7 mm)	95.61 in (2,428.5 mm)	+1.05 in (+26.7 mm)	+1.11%
Revolutions per mile	670	663	−7	−1.10%

True speed with the speedometer calibrated for 285/45R20
Indicated	Actual on 285/45R20	Actual on 265/50R20	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	75.8 mph	+0.8 mph

Ride-height change: 265/50R20 raises the vehicle by 0.17 in (4.3 mm) at the axle (half the +8.5 mm diameter difference).

265/50R20 is 0.33 in taller than 285/45R20 and 20 mm narrower, a 1.11% difference in overall diameter.

With the speedometer calibrated for 285/45R20, an indicated 60 mph is actually 60.7 mph on 265/50R20, and revolutions per mile change from 670 to 663.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 285/45R20

Other comparisons with 265/50R20

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