TireSizesFinder

285/40R18 vs 225/45R19

225/45R19 is 0.00 in (0.1 mm) shorter than 285/40R18, a −0.01% diameter difference. With the speedometer set for 285/40R18, an indicated 60 mph is 60.0 mph on 225/45R19.

Is this a safe swap?

Diameter difference −0.01%: under 1%

By overall diameter alone, 225/45R19 is a near match for 285/40R18; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 285/40R18 (26.98 in) vs 225/45R19 (26.97 in)285/40R1826.98 in × 11.22 in225/45R1926.97 in × 8.86 in
Side profile and tread width, drawn to the same scale.
285/40R18 vs 225/45R19 differences
Measurement285/40R18225/45R19Difference% diff
Overall diameter26.98 in (685.2 mm)26.97 in (685.1 mm)0.00 in (−0.1 mm)−0.01%
Sidewall height4.49 in (114.0 mm)3.99 in (101.3 mm)−0.50 in (−12.7 mm)−11.18%
Section width11.22 in (285.0 mm)8.86 in (225.0 mm)−2.36 in (−60.0 mm)−21.05%
Circumference84.75 in (2,152.6 mm)84.74 in (2,152.3 mm)−0.01 in (−0.3 mm)−0.01%
Revolutions per mile7487480+0.01%
True speed with the speedometer calibrated for 285/40R18
IndicatedActual on 285/40R18Actual on 225/45R19Difference
30 mph30.0 mph30.0 mph0.0 mph
60 mph60.0 mph60.0 mph0.0 mph
75 mph75.0 mph75.0 mph0.0 mph

Ride-height change: 225/45R19 lowers the vehicle by 0.00 in (0.1 mm) at the axle (half the −0.1 mm diameter difference).

225/45R19 is the same height as 285/40R18 and 60 mm narrower, a 0.01% difference in overall diameter.

With the speedometer calibrated for 285/40R18, an indicated 60 mph is actually 60.0 mph on 225/45R19, and revolutions per mile change from 748 to 748.

225/45R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 285/40R18.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.