255/35R18 vs 265/30R19

265/30R19 is 0.23 in (5.9 mm) taller than 255/35R18, a +0.93% diameter difference. With the speedometer set for 255/35R18, an indicated 60 mph is 60.6 mph on 265/30R19.

Is this a safe swap?

Diameter difference +0.93%: under 1%

By overall diameter alone, 265/30R19 is a near match for 255/35R18; 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.

255/35R18 vs 265/30R19 differences
Measurement	255/35R18	265/30R19	Difference	% diff
Overall diameter	25.03 in (635.7 mm)	25.26 in (641.6 mm)	+0.23 in (+5.9 mm)	+0.93%
Sidewall height	3.51 in (89.3 mm)	3.13 in (79.5 mm)	−0.38 in (−9.7 mm)	−10.92%
Section width	10.04 in (255.0 mm)	10.43 in (265.0 mm)	+0.39 in (+10.0 mm)	+3.92%
Circumference	78.63 in (1,997.1 mm)	79.36 in (2,015.6 mm)	+0.73 in (+18.5 mm)	+0.93%
Revolutions per mile	806	798	−7	−0.92%

True speed with the speedometer calibrated for 255/35R18
Indicated	Actual on 255/35R18	Actual on 265/30R19	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	75.7 mph	+0.7 mph

Ride-height change: 265/30R19 raises the vehicle by 0.12 in (2.9 mm) at the axle (half the +5.9 mm diameter difference).

265/30R19 is 0.23 in taller than 255/35R18 and 10 mm wider, a 0.93% difference in overall diameter.

With the speedometer calibrated for 255/35R18, an indicated 60 mph is actually 60.6 mph on 265/30R19, and revolutions per mile change from 806 to 798.

265/30R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 255/35R18.

Size pages

Other comparisons with 255/35R18

Other comparisons with 265/30R19

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