255/40R20 vs 265/30R22

265/30R22 is 0.23 in (5.8 mm) taller than 255/40R20, a +0.81% diameter difference. With the speedometer set for 255/40R20, an indicated 60 mph is 60.5 mph on 265/30R22.

Is this a safe swap?

Diameter difference +0.81%: under 1%

By overall diameter alone, 265/30R22 is a near match for 255/40R20; 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.

255/40R20 vs 265/30R22 differences
Measurement	255/40R20	265/30R22	Difference	% diff
Overall diameter	28.03 in (712.0 mm)	28.26 in (717.8 mm)	+0.23 in (+5.8 mm)	+0.81%
Sidewall height	4.02 in (102.0 mm)	3.13 in (79.5 mm)	−0.89 in (−22.5 mm)	−22.06%
Section width	10.04 in (255.0 mm)	10.43 in (265.0 mm)	+0.39 in (+10.0 mm)	+3.92%
Circumference	88.06 in (2,236.8 mm)	88.78 in (2,255.0 mm)	+0.72 in (+18.2 mm)	+0.81%
Revolutions per mile	719	714	−6	−0.81%

True speed with the speedometer calibrated for 255/40R20
Indicated	Actual on 255/40R20	Actual on 265/30R22	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.5 mph	+0.5 mph
75 mph	75.0 mph	75.6 mph	+0.6 mph

Ride-height change: 265/30R22 raises the vehicle by 0.11 in (2.9 mm) at the axle (half the +5.8 mm diameter difference).

265/30R22 is 0.23 in taller than 255/40R20 and 10 mm wider, a 0.81% difference in overall diameter.

With the speedometer calibrated for 255/40R20, an indicated 60 mph is actually 60.5 mph on 265/30R22, and revolutions per mile change from 719 to 714.

265/30R22 mounts on a 22-inch wheel, a plus-2 fitment from the 20-inch wheel of 255/40R20.

Size pages

Other comparisons with 255/40R20

Other comparisons with 265/30R22

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