295/35R20 vs 265/35R21

265/35R21 is 0.17 in (4.4 mm) taller than 295/35R20, a +0.62% diameter difference. With the speedometer set for 295/35R20, an indicated 60 mph is 60.4 mph on 265/35R21.

Is this a safe swap?

Diameter difference +0.62%: under 1%

By overall diameter alone, 265/35R21 is a near match for 295/35R20; 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.

295/35R20 vs 265/35R21 differences
Measurement	295/35R20	265/35R21	Difference	% diff
Overall diameter	28.13 in (714.5 mm)	28.30 in (718.9 mm)	+0.17 in (+4.4 mm)	+0.62%
Sidewall height	4.06 in (103.3 mm)	3.65 in (92.8 mm)	−0.41 in (−10.5 mm)	−10.17%
Section width	11.61 in (295.0 mm)	10.43 in (265.0 mm)	−1.18 in (−30.0 mm)	−10.17%
Circumference	88.37 in (2,244.7 mm)	88.92 in (2,258.5 mm)	+0.54 in (+13.8 mm)	+0.62%
Revolutions per mile	717	713	−4	−0.61%

True speed with the speedometer calibrated for 295/35R20
Indicated	Actual on 295/35R20	Actual on 265/35R21	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	75.5 mph	+0.5 mph

Ride-height change: 265/35R21 raises the vehicle by 0.09 in (2.2 mm) at the axle (half the +4.4 mm diameter difference).

265/35R21 is 0.17 in taller than 295/35R20 and 30 mm narrower, a 0.62% difference in overall diameter.

With the speedometer calibrated for 295/35R20, an indicated 60 mph is actually 60.4 mph on 265/35R21, and revolutions per mile change from 717 to 713.

265/35R21 mounts on a 21-inch wheel, a plus-1 fitment from the 20-inch wheel of 295/35R20.

Size pages

Other comparisons with 295/35R20

Other comparisons with 265/35R21

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