305/50R20 vs 265/60R20

265/60R20 is 0.51 in (13.0 mm) taller than 305/50R20, a +1.60% diameter difference. With the speedometer set for 305/50R20, an indicated 60 mph is 61.0 mph on 265/60R20.

Is this a safe swap?

Diameter difference +1.60%: within the ±3% guideline

By overall diameter alone, 265/60R20 falls inside the ±3% range commonly used as a guideline when replacing 305/50R20. 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.

305/50R20 vs 265/60R20 differences
Measurement	305/50R20	265/60R20	Difference	% diff
Overall diameter	32.01 in (813.0 mm)	32.52 in (826.0 mm)	+0.51 in (+13.0 mm)	+1.60%
Sidewall height	6.00 in (152.5 mm)	6.26 in (159.0 mm)	+0.26 in (+6.5 mm)	+4.26%
Section width	12.01 in (305.0 mm)	10.43 in (265.0 mm)	−1.57 in (−40.0 mm)	−13.11%
Circumference	100.56 in (2,554.1 mm)	102.16 in (2,595.0 mm)	+1.61 in (+40.8 mm)	+1.60%
Revolutions per mile	630	620	−10	−1.57%

True speed with the speedometer calibrated for 305/50R20
Indicated	Actual on 305/50R20	Actual on 265/60R20	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	61.0 mph	+1.0 mph
75 mph	75.0 mph	76.2 mph	+1.2 mph

Ride-height change: 265/60R20 raises the vehicle by 0.26 in (6.5 mm) at the axle (half the +13.0 mm diameter difference).

265/60R20 is 0.51 in taller than 305/50R20 and 40 mm narrower, a 1.60% difference in overall diameter.

With the speedometer calibrated for 305/50R20, an indicated 60 mph is actually 61.0 mph on 265/60R20, and revolutions per mile change from 630 to 620.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 305/50R20

Other comparisons with 265/60R20

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