225/40R18 vs 265/30R19

265/30R19 is 0.17 in (4.4 mm) taller than 225/40R18, a +0.69% diameter difference. With the speedometer set for 225/40R18, an indicated 60 mph is 60.4 mph on 265/30R19.

Is this a safe swap?

Diameter difference +0.69%: under 1%

By overall diameter alone, 265/30R19 is a near match for 225/40R18; 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.

225/40R18 vs 265/30R19 differences
Measurement	225/40R18	265/30R19	Difference	% diff
Overall diameter	25.09 in (637.2 mm)	25.26 in (641.6 mm)	+0.17 in (+4.4 mm)	+0.69%
Sidewall height	3.54 in (90.0 mm)	3.13 in (79.5 mm)	−0.41 in (−10.5 mm)	−11.67%
Section width	8.86 in (225.0 mm)	10.43 in (265.0 mm)	+1.57 in (+40.0 mm)	+17.78%
Circumference	78.81 in (2,001.8 mm)	79.36 in (2,015.6 mm)	+0.54 in (+13.8 mm)	+0.69%
Revolutions per mile	804	798	−6	−0.69%

True speed with the speedometer calibrated for 225/40R18
Indicated	Actual on 225/40R18	Actual on 265/30R19	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: 265/30R19 raises the vehicle by 0.09 in (2.2 mm) at the axle (half the +4.4 mm diameter difference).

265/30R19 is 0.17 in taller than 225/40R18 and 40 mm wider, a 0.69% difference in overall diameter.

With the speedometer calibrated for 225/40R18, an indicated 60 mph is actually 60.4 mph on 265/30R19, and revolutions per mile change from 804 to 798.

265/30R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 225/40R18.

Size pages

Other comparisons with 225/40R18

Other comparisons with 265/30R19

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