TireSizesFinder

235/40R17 vs 245/30R19

245/30R19 is 0.39 in (9.8 mm) taller than 235/40R17, a +1.58% diameter difference. With the speedometer set for 235/40R17, an indicated 60 mph is 60.9 mph on 245/30R19.

Is this a safe swap?

Diameter difference +1.58%: within the ±3% guideline

By overall diameter alone, 245/30R19 falls inside the ±3% range commonly used as a guideline when replacing 235/40R17. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 235/40R17 (24.40 in) vs 245/30R19 (24.79 in)235/40R1724.40 in × 9.25 in245/30R1924.79 in × 9.65 in
Side profile and tread width, drawn to the same scale.
235/40R17 vs 245/30R19 differences
Measurement235/40R17245/30R19Difference% diff
Overall diameter24.40 in (619.8 mm)24.79 in (629.6 mm)+0.39 in (+9.8 mm)+1.58%
Sidewall height3.70 in (94.0 mm)2.89 in (73.5 mm)−0.81 in (−20.5 mm)−21.81%
Section width9.25 in (235.0 mm)9.65 in (245.0 mm)+0.39 in (+10.0 mm)+4.26%
Circumference76.66 in (1,947.2 mm)77.87 in (1,977.9 mm)+1.21 in (+30.8 mm)+1.58%
Revolutions per mile827814−13−1.56%
True speed with the speedometer calibrated for 235/40R17
IndicatedActual on 235/40R17Actual on 245/30R19Difference
30 mph30.0 mph30.5 mph+0.5 mph
60 mph60.0 mph60.9 mph+0.9 mph
75 mph75.0 mph76.2 mph+1.2 mph

Ride-height change: 245/30R19 raises the vehicle by 0.19 in (4.9 mm) at the axle (half the +9.8 mm diameter difference).

245/30R19 is 0.39 in taller than 235/40R17 and 10 mm wider, a 1.58% difference in overall diameter.

With the speedometer calibrated for 235/40R17, an indicated 60 mph is actually 60.9 mph on 245/30R19, and revolutions per mile change from 827 to 814.

245/30R19 mounts on a 19-inch wheel, a plus-2 fitment from the 17-inch wheel of 235/40R17.

Size pages

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