Tire Size Box

325/35R19 vs 325/40R19

325/40R19 compared with 325/35R19

+4.6% diameter, 0.0" width

325/40R19 is 29.24" tall vs 27.96". More than the 3% rule of thumb, so check carefully before switching.

28.0"19" rim4.5"12.8" wide
325/35R19 (solid) compared with 325/40R19 (dashed outline), drawn to scale

With 325/40R19 tires, when your speedometer says 60 mph you are really going

62.7 mph

325/40R19 is +1.28 inches (+4.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

325/35R19325/40R19Difference%
Overall diameter27.96"29.24"+1.28"+4.6%
Section width12.80"12.80"0.00"0.0%
Sidewall height4.48"5.12"+0.64"+14.3%
Circumference87.83"91.85"+4.02"+4.6%
Revolutions per mile721.4689.8−31.6−4.4%

Speedometer difference

If your vehicle came with 325/35R19 and you fit 325/40R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.9 mph+0.9 mph
30 mph31.4 mph+1.4 mph
40 mph41.8 mph+1.8 mph
50 mph52.3 mph+2.3 mph
60 mph62.7 mph+2.7 mph
65 mph68.0 mph+3.0 mph
70 mph73.2 mph+3.2 mph
75 mph78.4 mph+3.4 mph
80 mph83.7 mph+3.7 mph

Each size on its own

Questions

Which is bigger, 325/35R19 or 325/40R19?
325/40R19 is taller by 1.28 inches (29.24" vs 27.96"). 325/35R19 is the same width.
Can I replace 325/35R19 with 325/40R19?
It is not recommended without checking carefully. The diameter difference is +4.6%, 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 325/40R19 change my speedometer?
When your speedometer reads 60 mph with 325/40R19 fitted (calibrated for 325/35R19), your real speed is 62.7 mph. Your odometer will under-count miles by about 4.6%.
Will 325/40R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.64 inches of ground clearance at the axle.

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