305/45R22 vs 325/45R22

325/45R22 is 0.71 in (18.0 mm) taller than 305/45R22, a +2.16% diameter difference. With the speedometer set for 305/45R22, an indicated 60 mph is 61.3 mph on 325/45R22.

Is this a safe swap?

Diameter difference +2.16%: within the ±3% guideline

By overall diameter alone, 325/45R22 falls inside the ±3% range commonly used as a guideline when replacing 305/45R22. 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.

305/45R22 vs 325/45R22 differences
Measurement	305/45R22	325/45R22	Difference	% diff
Overall diameter	32.81 in (833.3 mm)	33.52 in (851.3 mm)	+0.71 in (+18.0 mm)	+2.16%
Sidewall height	5.40 in (137.3 mm)	5.76 in (146.3 mm)	+0.35 in (+9.0 mm)	+6.56%
Section width	12.01 in (305.0 mm)	12.80 in (325.0 mm)	+0.79 in (+20.0 mm)	+6.56%
Circumference	103.07 in (2,617.9 mm)	105.29 in (2,674.4 mm)	+2.23 in (+56.5 mm)	+2.16%
Revolutions per mile	615	602	−13	−2.11%

True speed with the speedometer calibrated for 305/45R22
Indicated	Actual on 305/45R22	Actual on 325/45R22	Difference
30 mph	30.0 mph	30.6 mph	+0.6 mph
60 mph	60.0 mph	61.3 mph	+1.3 mph
75 mph	75.0 mph	76.6 mph	+1.6 mph

Ride-height change: 325/45R22 raises the vehicle by 0.35 in (9.0 mm) at the axle (half the +18.0 mm diameter difference).

325/45R22 is 0.71 in taller than 305/45R22 and 20 mm wider, a 2.16% difference in overall diameter.

With the speedometer calibrated for 305/45R22, an indicated 60 mph is actually 61.3 mph on 325/45R22, and revolutions per mile change from 615 to 602.

Both sizes mount on 22-inch wheels.

Size pages

Other comparisons with 305/45R22

Other comparisons with 325/45R22

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