Tire Size Box

355/35R24 vs 355/40R24

355/40R24 compared with 355/35R24

+4.1% diameter, 0.0" width

355/40R24 is 35.18" tall vs 33.78". More than the 3% rule of thumb, so check carefully before switching.

33.8"24" rim4.9"14.0" wide
355/35R24 (solid) compared with 355/40R24 (dashed outline), drawn to scale

With 355/40R24 tires, when your speedometer says 60 mph you are really going

62.5 mph

355/40R24 is +1.40 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/35R24355/40R24Difference%
Overall diameter33.78"35.18"+1.40"+4.1%
Section width13.98"13.98"0.00"0.0%
Sidewall height4.89"5.59"+0.70"+14.3%
Circumference106.13"110.52"+4.39"+4.1%
Revolutions per mile597.0573.3−23.7−4.0%

Speedometer difference

If your vehicle came with 355/35R24 and you fit 355/40R24, 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 mph41.7 mph+1.7 mph
50 mph52.1 mph+2.1 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 mph
70 mph72.9 mph+2.9 mph
75 mph78.1 mph+3.1 mph
80 mph83.3 mph+3.3 mph

Each size on its own

Questions

Which is bigger, 355/35R24 or 355/40R24?
355/40R24 is taller by 1.40 inches (35.18" vs 33.78"). 355/35R24 is the same width.
Can I replace 355/35R24 with 355/40R24?
It is not recommended without checking carefully. The diameter difference is +4.1%, 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 355/40R24 change my speedometer?
When your speedometer reads 60 mph with 355/40R24 fitted (calibrated for 355/35R24), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.1%.
Will 355/40R24 lift my vehicle?
Ride height changes by half the diameter difference: +0.70 inches of ground clearance at the axle.

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