245/55R17 vs 235/45R19

235/45R19 is 0.28 in (7.2 mm) shorter than 245/55R17, a −1.03% diameter difference. With the speedometer set for 245/55R17, an indicated 60 mph is 59.4 mph on 235/45R19.

Is this a safe swap?

Diameter difference −1.03%: within the ±3% guideline

By overall diameter alone, 235/45R19 falls inside the ±3% range commonly used as a guideline when replacing 245/55R17. 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.

245/55R17 vs 235/45R19 differences
Measurement	245/55R17	235/45R19	Difference	% diff
Overall diameter	27.61 in (701.3 mm)	27.33 in (694.1 mm)	−0.28 in (−7.2 mm)	−1.03%
Sidewall height	5.31 in (134.8 mm)	4.16 in (105.8 mm)	−1.14 in (−29.0 mm)	−21.52%
Section width	9.65 in (245.0 mm)	9.25 in (235.0 mm)	−0.39 in (−10.0 mm)	−4.08%
Circumference	86.74 in (2,203.2 mm)	85.85 in (2,180.6 mm)	−0.89 in (−22.6 mm)	−1.03%
Revolutions per mile	730	738	+8	+1.04%

True speed with the speedometer calibrated for 245/55R17
Indicated	Actual on 245/55R17	Actual on 235/45R19	Difference
30 mph	30.0 mph	29.7 mph	−0.3 mph
60 mph	60.0 mph	59.4 mph	−0.6 mph
75 mph	75.0 mph	74.2 mph	−0.8 mph

Ride-height change: 235/45R19 lowers the vehicle by 0.14 in (3.6 mm) at the axle (half the −7.2 mm diameter difference).

235/45R19 is 0.28 in shorter than 245/55R17 and 10 mm narrower, a 1.03% difference in overall diameter.

With the speedometer calibrated for 245/55R17, an indicated 60 mph is actually 59.4 mph on 235/45R19, and revolutions per mile change from 730 to 738.

235/45R19 mounts on a 19-inch wheel, a plus-2 fitment from the 17-inch wheel of 245/55R17.

Size pages

Other comparisons with 245/55R17

Other comparisons with 235/45R19

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