255/40R17 vs 265/30R19

265/30R19 is 0.23 in (5.8 mm) taller than 255/40R17, a +0.91% diameter difference. With the speedometer set for 255/40R17, an indicated 60 mph is 60.5 mph on 265/30R19.

Is this a safe swap?

Diameter difference +0.91%: under 1%

By overall diameter alone, 265/30R19 is a near match for 255/40R17; 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.

255/40R17 vs 265/30R19 differences
Measurement	255/40R17	265/30R19	Difference	% diff
Overall diameter	25.03 in (635.8 mm)	25.26 in (641.6 mm)	+0.23 in (+5.8 mm)	+0.91%
Sidewall height	4.02 in (102.0 mm)	3.13 in (79.5 mm)	−0.89 in (−22.5 mm)	−22.06%
Section width	10.04 in (255.0 mm)	10.43 in (265.0 mm)	+0.39 in (+10.0 mm)	+3.92%
Circumference	78.64 in (1,997.4 mm)	79.36 in (2,015.6 mm)	+0.72 in (+18.2 mm)	+0.91%
Revolutions per mile	806	798	−7	−0.90%

True speed with the speedometer calibrated for 255/40R17
Indicated	Actual on 255/40R17	Actual on 265/30R19	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.5 mph	+0.5 mph
75 mph	75.0 mph	75.7 mph	+0.7 mph

Ride-height change: 265/30R19 raises the vehicle by 0.11 in (2.9 mm) at the axle (half the +5.8 mm diameter difference).

265/30R19 is 0.23 in taller than 255/40R17 and 10 mm wider, a 0.91% difference in overall diameter.

With the speedometer calibrated for 255/40R17, an indicated 60 mph is actually 60.5 mph on 265/30R19, and revolutions per mile change from 806 to 798.

265/30R19 mounts on a 19-inch wheel, a plus-2 fitment from the 17-inch wheel of 255/40R17.

Size pages

Other comparisons with 255/40R17

Other comparisons with 265/30R19

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