265/35R21 vs 275/35R21

275/35R21 is 0.28 in (7.0 mm) taller than 265/35R21, a +0.97% diameter difference. With the speedometer set for 265/35R21, an indicated 60 mph is 60.6 mph on 275/35R21.

Is this a safe swap?

Diameter difference +0.97%: under 1%

By overall diameter alone, 275/35R21 is a near match for 265/35R21; 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.

265/35R21 vs 275/35R21 differences
Measurement	265/35R21	275/35R21	Difference	% diff
Overall diameter	28.30 in (718.9 mm)	28.58 in (725.9 mm)	+0.28 in (+7.0 mm)	+0.97%
Sidewall height	3.65 in (92.8 mm)	3.79 in (96.3 mm)	+0.14 in (+3.5 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	88.92 in (2,258.5 mm)	89.78 in (2,280.5 mm)	+0.87 in (+22.0 mm)	+0.97%
Revolutions per mile	713	706	−7	−0.96%

True speed with the speedometer calibrated for 265/35R21
Indicated	Actual on 265/35R21	Actual on 275/35R21	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.6 mph	+0.6 mph
75 mph	75.0 mph	75.7 mph	+0.7 mph

Ride-height change: 275/35R21 raises the vehicle by 0.14 in (3.5 mm) at the axle (half the +7.0 mm diameter difference).

275/35R21 is 0.28 in taller than 265/35R21 and 10 mm wider, a 0.97% difference in overall diameter.

With the speedometer calibrated for 265/35R21, an indicated 60 mph is actually 60.6 mph on 275/35R21, and revolutions per mile change from 713 to 706.

Both sizes mount on 21-inch wheels.

Size pages

Other comparisons with 265/35R21

Other comparisons with 275/35R21

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