Tire Size Box

245/35R19 vs 245/40R19

245/40R19 compared with 245/35R19

+3.7% diameter, 0.0" width

245/40R19 is 26.72" tall vs 25.75". More than the 3% rule of thumb, so check carefully before switching.

25.8"19" rim3.4"9.6" wide
245/35R19 (solid) compared with 245/40R19 (dashed outline), drawn to scale

With 245/40R19 tires, when your speedometer says 60 mph you are really going

62.2 mph

245/40R19 is +0.96 inches (+3.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/35R19245/40R19Difference%
Overall diameter25.75"26.72"+0.96"+3.7%
Section width9.65"9.65"0.00"0.0%
Sidewall height3.38"3.86"+0.48"+14.3%
Circumference80.90"83.93"+3.03"+3.7%
Revolutions per mile783.2754.9−28.3−3.6%

Speedometer difference

If your vehicle came with 245/35R19 and you fit 245/40R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.6 mph+2.6 mph
75 mph77.8 mph+2.8 mph
80 mph83.0 mph+3.0 mph

Each size on its own

Questions

Which is bigger, 245/35R19 or 245/40R19?
245/40R19 is taller by 0.96 inches (26.72" vs 25.75"). 245/35R19 is the same width.
Can I replace 245/35R19 with 245/40R19?
It is not recommended without checking carefully. The diameter difference is +3.7%, more than the 3% most shops and makers allow. It will throw off the speedometer and may affect ABS, stability control and clearance.
How much will 245/40R19 change my speedometer?
When your speedometer reads 60 mph with 245/40R19 fitted (calibrated for 245/35R19), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.7%.
Will 245/40R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.48 inches of ground clearance at the axle.

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