265/30R20 vs 275/30R20

275/30R20 is 0.24 in (6.0 mm) taller than 265/30R20, a +0.90% diameter difference. With the speedometer set for 265/30R20, an indicated 60 mph is 60.5 mph on 275/30R20.

Is this a safe swap?

Diameter difference +0.90%: under 1%

By overall diameter alone, 275/30R20 is a near match for 265/30R20; 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.

265/30R20 vs 275/30R20 differences
Measurement	265/30R20	275/30R20	Difference	% diff
Overall diameter	26.26 in (667.0 mm)	26.50 in (673.0 mm)	+0.24 in (+6.0 mm)	+0.90%
Sidewall height	3.13 in (79.5 mm)	3.25 in (82.5 mm)	+0.12 in (+3.0 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	82.50 in (2,095.4 mm)	83.24 in (2,114.3 mm)	+0.74 in (+18.8 mm)	+0.90%
Revolutions per mile	768	761	−7	−0.89%

True speed with the speedometer calibrated for 265/30R20
Indicated	Actual on 265/30R20	Actual on 275/30R20	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: 275/30R20 raises the vehicle by 0.12 in (3.0 mm) at the axle (half the +6.0 mm diameter difference).

275/30R20 is 0.24 in taller than 265/30R20 and 10 mm wider, a 0.90% difference in overall diameter.

With the speedometer calibrated for 265/30R20, an indicated 60 mph is actually 60.5 mph on 275/30R20, and revolutions per mile change from 768 to 761.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 265/30R20

Other comparisons with 275/30R20

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