265/35R19 vs 275/30R20

275/30R20 is 0.19 in (4.9 mm) taller than 265/35R19, a +0.73% diameter difference. With the speedometer set for 265/35R19, an indicated 60 mph is 60.4 mph on 275/30R20.

Is this a safe swap?

Diameter difference +0.73%: under 1%

By overall diameter alone, 275/30R20 is a near match for 265/35R19; 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.

265/35R19 vs 275/30R20 differences
Measurement	265/35R19	275/30R20	Difference	% diff
Overall diameter	26.30 in (668.1 mm)	26.50 in (673.0 mm)	+0.19 in (+4.9 mm)	+0.73%
Sidewall height	3.65 in (92.8 mm)	3.25 in (82.5 mm)	−0.40 in (−10.2 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	82.63 in (2,098.9 mm)	83.24 in (2,114.3 mm)	+0.61 in (+15.4 mm)	+0.73%
Revolutions per mile	767	761	−6	−0.73%

True speed with the speedometer calibrated for 265/35R19
Indicated	Actual on 265/35R19	Actual on 275/30R20	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.4 mph	+0.4 mph
75 mph	75.0 mph	75.6 mph	+0.6 mph

Ride-height change: 275/30R20 raises the vehicle by 0.10 in (2.5 mm) at the axle (half the +4.9 mm diameter difference).

275/30R20 is 0.19 in taller than 265/35R19 and 10 mm wider, a 0.73% difference in overall diameter.

With the speedometer calibrated for 265/35R19, an indicated 60 mph is actually 60.4 mph on 275/30R20, and revolutions per mile change from 767 to 761.

275/30R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 265/35R19.

Size pages

Other comparisons with 265/35R19

Other comparisons with 275/30R20

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