265/40R20 vs 275/40R20

275/40R20 is 0.31 in (8.0 mm) taller than 265/40R20, a +1.11% diameter difference. With the speedometer set for 265/40R20, an indicated 60 mph is 60.7 mph on 275/40R20.

Is this a safe swap?

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

By overall diameter alone, 275/40R20 falls inside the ±3% range commonly used as a guideline when replacing 265/40R20. 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.

265/40R20 vs 275/40R20 differences
Measurement	265/40R20	275/40R20	Difference	% diff
Overall diameter	28.35 in (720.0 mm)	28.66 in (728.0 mm)	+0.31 in (+8.0 mm)	+1.11%
Sidewall height	4.17 in (106.0 mm)	4.33 in (110.0 mm)	+0.16 in (+4.0 mm)	+3.77%
Section width	10.43 in (265.0 mm)	10.83 in (275.0 mm)	+0.39 in (+10.0 mm)	+3.77%
Circumference	89.05 in (2,261.9 mm)	90.04 in (2,287.1 mm)	+0.99 in (+25.1 mm)	+1.11%
Revolutions per mile	711	704	−8	−1.10%

True speed with the speedometer calibrated for 265/40R20
Indicated	Actual on 265/40R20	Actual on 275/40R20	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: 275/40R20 raises the vehicle by 0.16 in (4.0 mm) at the axle (half the +8.0 mm diameter difference).

275/40R20 is 0.31 in taller than 265/40R20 and 10 mm wider, a 1.11% difference in overall diameter.

With the speedometer calibrated for 265/40R20, an indicated 60 mph is actually 60.7 mph on 275/40R20, and revolutions per mile change from 711 to 704.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 265/40R20

Other comparisons with 275/40R20

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