265/45R19 vs 325/30R21

325/30R21 is 0.29 in (7.3 mm) taller than 265/45R19, a +1.01% diameter difference. With the speedometer set for 265/45R19, an indicated 60 mph is 60.6 mph on 325/30R21.

Is this a safe swap?

Diameter difference +1.01%: within the ±3% guideline

By overall diameter alone, 325/30R21 falls inside the ±3% range commonly used as a guideline when replacing 265/45R19. 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.

265/45R19 vs 325/30R21 differences
Measurement	265/45R19	325/30R21	Difference	% diff
Overall diameter	28.39 in (721.1 mm)	28.68 in (728.4 mm)	+0.29 in (+7.3 mm)	+1.01%
Sidewall height	4.69 in (119.3 mm)	3.84 in (97.5 mm)	−0.86 in (−21.7 mm)	−18.24%
Section width	10.43 in (265.0 mm)	12.80 in (325.0 mm)	+2.36 in (+60.0 mm)	+22.64%
Circumference	89.19 in (2,265.4 mm)	90.09 in (2,288.3 mm)	+0.90 in (+22.9 mm)	+1.01%
Revolutions per mile	710	703	−7	−1.00%

True speed with the speedometer calibrated for 265/45R19
Indicated	Actual on 265/45R19	Actual on 325/30R21	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	75.8 mph	+0.8 mph

Ride-height change: 325/30R21 raises the vehicle by 0.14 in (3.7 mm) at the axle (half the +7.3 mm diameter difference).

325/30R21 is 0.29 in taller than 265/45R19 and 60 mm wider, a 1.01% difference in overall diameter.

With the speedometer calibrated for 265/45R19, an indicated 60 mph is actually 60.6 mph on 325/30R21, and revolutions per mile change from 710 to 703.

325/30R21 mounts on a 21-inch wheel, a plus-2 fitment from the 19-inch wheel of 265/45R19.

Size pages

Other comparisons with 265/45R19

Other comparisons with 325/30R21

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