TireSizesFinder

245/40R19 vs 235/35R20

235/35R20 is 0.24 in (6.1 mm) shorter than 245/40R19, a −0.90% diameter difference. With the speedometer set for 245/40R19, an indicated 60 mph is 59.5 mph on 235/35R20.

Is this a safe swap?

Diameter difference −0.90%: under 1%

By overall diameter alone, 235/35R20 is a near match for 245/40R19; 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: 245/40R19 (26.72 in) vs 235/35R20 (26.48 in)245/40R1926.72 in × 9.65 in235/35R2026.48 in × 9.25 in
Side profile and tread width, drawn to the same scale.
245/40R19 vs 235/35R20 differences
Measurement245/40R19235/35R20Difference% diff
Overall diameter26.72 in (678.6 mm)26.48 in (672.5 mm)−0.24 in (−6.1 mm)−0.90%
Sidewall height3.86 in (98.0 mm)3.24 in (82.3 mm)−0.62 in (−15.7 mm)−16.07%
Section width9.65 in (245.0 mm)9.25 in (235.0 mm)−0.39 in (−10.0 mm)−4.08%
Circumference83.93 in (2,131.9 mm)83.18 in (2,112.7 mm)−0.75 in (−19.2 mm)−0.90%
Revolutions per mile755762+7+0.91%
True speed with the speedometer calibrated for 245/40R19
IndicatedActual on 245/40R19Actual on 235/35R20Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.3 mph−0.7 mph

Ride-height change: 235/35R20 lowers the vehicle by 0.12 in (3.0 mm) at the axle (half the −6.1 mm diameter difference).

235/35R20 is 0.24 in shorter than 245/40R19 and 10 mm narrower, a 0.90% difference in overall diameter.

With the speedometer calibrated for 245/40R19, an indicated 60 mph is actually 59.5 mph on 235/35R20, and revolutions per mile change from 755 to 762.

235/35R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 245/40R19.

Size pages

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