295/40R18 vs 235/45R19

235/45R19 is 0.04 in (0.9 mm) taller than 295/40R18, a +0.13% diameter difference. With the speedometer set for 295/40R18, an indicated 60 mph is 60.1 mph on 235/45R19.

Is this a safe swap?

Diameter difference +0.13%: under 1%

By overall diameter alone, 235/45R19 is a near match for 295/40R18; 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.

295/40R18 vs 235/45R19 differences
Measurement	295/40R18	235/45R19	Difference	% diff
Overall diameter	27.29 in (693.2 mm)	27.33 in (694.1 mm)	+0.04 in (+0.9 mm)	+0.13%
Sidewall height	4.65 in (118.0 mm)	4.16 in (105.8 mm)	−0.48 in (−12.2 mm)	−10.38%
Section width	11.61 in (295.0 mm)	9.25 in (235.0 mm)	−2.36 in (−60.0 mm)	−20.34%
Circumference	85.74 in (2,177.8 mm)	85.85 in (2,180.6 mm)	+0.11 in (+2.8 mm)	+0.13%
Revolutions per mile	739	738	−1	−0.13%

True speed with the speedometer calibrated for 295/40R18
Indicated	Actual on 295/40R18	Actual on 235/45R19	Difference
30 mph	30.0 mph	30.0 mph	0.0 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: 235/45R19 raises the vehicle by 0.02 in (0.4 mm) at the axle (half the +0.9 mm diameter difference).

235/45R19 is 0.04 in taller than 295/40R18 and 60 mm narrower, a 0.13% difference in overall diameter.

With the speedometer calibrated for 295/40R18, an indicated 60 mph is actually 60.1 mph on 235/45R19, and revolutions per mile change from 739 to 738.

235/45R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 295/40R18.

Size pages

Other comparisons with 295/40R18

Other comparisons with 235/45R19

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