255/45R17 vs 225/40R19

225/40R19 is 0.05 in (1.3 mm) taller than 255/45R17, a +0.20% diameter difference. With the speedometer set for 255/45R17, an indicated 60 mph is 60.1 mph on 225/40R19.

Is this a safe swap?

Diameter difference +0.20%: under 1%

By overall diameter alone, 225/40R19 is a near match for 255/45R17; 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.

255/45R17 vs 225/40R19 differences
Measurement	255/45R17	225/40R19	Difference	% diff
Overall diameter	26.04 in (661.3 mm)	26.09 in (662.6 mm)	+0.05 in (+1.3 mm)	+0.20%
Sidewall height	4.52 in (114.8 mm)	3.54 in (90.0 mm)	−0.97 in (−24.7 mm)	−21.57%
Section width	10.04 in (255.0 mm)	8.86 in (225.0 mm)	−1.18 in (−30.0 mm)	−11.76%
Circumference	81.79 in (2,077.5 mm)	81.95 in (2,081.6 mm)	+0.16 in (+4.1 mm)	+0.20%
Revolutions per mile	775	773	−2	−0.20%

True speed with the speedometer calibrated for 255/45R17
Indicated	Actual on 255/45R17	Actual on 225/40R19	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.1 mph	+0.1 mph
75 mph	75.0 mph	75.1 mph	+0.1 mph

Ride-height change: 225/40R19 raises the vehicle by 0.03 in (0.6 mm) at the axle (half the +1.3 mm diameter difference).

225/40R19 is 0.05 in taller than 255/45R17 and 30 mm narrower, a 0.20% difference in overall diameter.

With the speedometer calibrated for 255/45R17, an indicated 60 mph is actually 60.1 mph on 225/40R19, and revolutions per mile change from 775 to 773.

225/40R19 mounts on a 19-inch wheel, a plus-2 fitment from the 17-inch wheel of 255/45R17.

Size pages

Other comparisons with 255/45R17

Other comparisons with 225/40R19

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