265/45R18 vs 305/35R19

305/35R19 is 0.02 in (0.4 mm) taller than 265/45R18, a +0.06% diameter difference. With the speedometer set for 265/45R18, an indicated 60 mph is 60.0 mph on 305/35R19.

Is this a safe swap?

Diameter difference +0.06%: under 1%

By overall diameter alone, 305/35R19 is a near match for 265/45R18; 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.

265/45R18 vs 305/35R19 differences
Measurement	265/45R18	305/35R19	Difference	% diff
Overall diameter	27.39 in (695.7 mm)	27.41 in (696.1 mm)	+0.02 in (+0.4 mm)	+0.06%
Sidewall height	4.69 in (119.3 mm)	4.20 in (106.8 mm)	−0.49 in (−12.5 mm)	−10.48%
Section width	10.43 in (265.0 mm)	12.01 in (305.0 mm)	+1.57 in (+40.0 mm)	+15.09%
Circumference	86.05 in (2,185.6 mm)	86.10 in (2,186.9 mm)	+0.05 in (+1.3 mm)	+0.06%
Revolutions per mile	736	736	0	−0.06%

True speed with the speedometer calibrated for 265/45R18
Indicated	Actual on 265/45R18	Actual on 305/35R19
30 mph	30.0 mph	30.0 mph
60 mph	60.0 mph	60.0 mph
75 mph	75.0 mph	75.0 mph

Ride-height change: 305/35R19 raises the vehicle by 0.01 in (0.2 mm) at the axle (half the +0.4 mm diameter difference).

305/35R19 is 0.02 in taller than 265/45R18 and 40 mm wider, a 0.06% difference in overall diameter.

With the speedometer calibrated for 265/45R18, an indicated 60 mph is actually 60.0 mph on 305/35R19, and revolutions per mile change from 736 to 736.

305/35R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 265/45R18.

Size pages

Other comparisons with 265/45R18

Other comparisons with 305/35R19

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