275/40R22 vs 305/30R24

305/30R24 is 0.54 in (13.8 mm) taller than 275/40R22, a +1.77% diameter difference. With the speedometer set for 275/40R22, an indicated 60 mph is 61.1 mph on 305/30R24.

Is this a safe swap?

Diameter difference +1.77%: within the ±3% guideline

By overall diameter alone, 305/30R24 falls inside the ±3% range commonly used as a guideline when replacing 275/40R22. 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.

275/40R22 vs 305/30R24 differences
Measurement	275/40R22	305/30R24	Difference	% diff
Overall diameter	30.66 in (778.8 mm)	31.20 in (792.6 mm)	+0.54 in (+13.8 mm)	+1.77%
Sidewall height	4.33 in (110.0 mm)	3.60 in (91.5 mm)	−0.73 in (−18.5 mm)	−16.82%
Section width	10.83 in (275.0 mm)	12.01 in (305.0 mm)	+1.18 in (+30.0 mm)	+10.91%
Circumference	96.33 in (2,446.7 mm)	98.03 in (2,490.0 mm)	+1.71 in (+43.4 mm)	+1.77%
Revolutions per mile	658	646	−11	−1.74%

True speed with the speedometer calibrated for 275/40R22
Indicated	Actual on 275/40R22	Actual on 305/30R24	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	61.1 mph	+1.1 mph
75 mph	75.0 mph	76.3 mph	+1.3 mph

Ride-height change: 305/30R24 raises the vehicle by 0.27 in (6.9 mm) at the axle (half the +13.8 mm diameter difference).

305/30R24 is 0.54 in taller than 275/40R22 and 30 mm wider, a 1.77% difference in overall diameter.

With the speedometer calibrated for 275/40R22, an indicated 60 mph is actually 61.1 mph on 305/30R24, and revolutions per mile change from 658 to 646.

305/30R24 mounts on a 24-inch wheel, a plus-2 fitment from the 22-inch wheel of 275/40R22.

Size pages

Other comparisons with 275/40R22

Other comparisons with 305/30R24

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