Tire Size Box

325/35R24 vs 325/40R24

325/40R24 compared with 325/35R24

+3.9% diameter, 0.0" width

325/40R24 is 34.24" tall vs 32.96". More than the 3% rule of thumb, so check carefully before switching.

33.0"24" rim4.5"12.8" wide
325/35R24 (solid) compared with 325/40R24 (dashed outline), drawn to scale

With 325/40R24 tires, when your speedometer says 60 mph you are really going

62.3 mph

325/40R24 is +1.28 inches (+3.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

325/35R24325/40R24Difference%
Overall diameter32.96"34.24"+1.28"+3.9%
Section width12.80"12.80"0.00"0.0%
Sidewall height4.48"5.12"+0.64"+14.3%
Circumference103.54"107.56"+4.02"+3.9%
Revolutions per mile612.0589.1−22.9−3.7%

Speedometer difference

If your vehicle came with 325/35R24 and you fit 325/40R24, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.6 mph+1.6 mph
50 mph51.9 mph+1.9 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.9 mph+2.9 mph
80 mph83.1 mph+3.1 mph

Each size on its own

Questions

Which is bigger, 325/35R24 or 325/40R24?
325/40R24 is taller by 1.28 inches (34.24" vs 32.96"). 325/35R24 is the same width.
Can I replace 325/35R24 with 325/40R24?
It is not recommended without checking carefully. The diameter difference is +3.9%, 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 325/40R24 change my speedometer?
When your speedometer reads 60 mph with 325/40R24 fitted (calibrated for 325/35R24), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.9%.
Will 325/40R24 lift my vehicle?
Ride height changes by half the diameter difference: +0.64 inches of ground clearance at the axle.

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