265/70R18 vs 275/60R20

275/60R20 is 0.39 in (9.8 mm) taller than 265/70R18, a +1.18% diameter difference. With the speedometer set for 265/70R18, an indicated 60 mph is 60.7 mph on 275/60R20.

Is this a safe swap?

Diameter difference +1.18%: within the ±3% guideline

By overall diameter alone, 275/60R20 falls inside the ±3% range commonly used as a guideline when replacing 265/70R18. 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.

265/70R18 vs 275/60R20 differences
Measurement	265/70R18	275/60R20	Difference	% diff
Overall diameter	32.61 in (828.2 mm)	32.99 in (838.0 mm)	+0.39 in (+9.8 mm)	+1.18%
Sidewall height	7.30 in (185.5 mm)	6.50 in (165.0 mm)	−0.81 in (−20.5 mm)	−11.05%
Section width	10.43 in (265.0 mm)	10.83 in (275.0 mm)	+0.39 in (+10.0 mm)	+3.77%
Circumference	102.44 in (2,601.9 mm)	103.65 in (2,632.7 mm)	+1.21 in (+30.8 mm)	+1.18%
Revolutions per mile	619	611	−7	−1.17%

True speed with the speedometer calibrated for 265/70R18
Indicated	Actual on 265/70R18	Actual on 275/60R20	Difference
30 mph	30.0 mph	30.4 mph	+0.4 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: 275/60R20 raises the vehicle by 0.19 in (4.9 mm) at the axle (half the +9.8 mm diameter difference).

275/60R20 is 0.39 in taller than 265/70R18 and 10 mm wider, a 1.18% difference in overall diameter.

With the speedometer calibrated for 265/70R18, an indicated 60 mph is actually 60.7 mph on 275/60R20, and revolutions per mile change from 619 to 611.

275/60R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 265/70R18.

Size pages

Other comparisons with 265/70R18

Other comparisons with 275/60R20

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