Tire Size Box

335/30R24 vs 335/40R24

335/40R24 compared with 335/30R24

+8.3% diameter, 0.0" width

335/40R24 is 34.55" tall vs 31.91". More than the 3% rule of thumb, so check carefully before switching.

31.9"24" rim4.0"13.2" wide
335/30R24 (solid) compared with 335/40R24 (dashed outline), drawn to scale

With 335/40R24 tires, when your speedometer says 60 mph you are really going

65.0 mph

335/40R24 is +2.64 inches (+8.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/30R24335/40R24Difference%
Overall diameter31.91"34.55"+2.64"+8.3%
Section width13.19"13.19"0.00"0.0%
Sidewall height3.96"5.28"+1.32"+33.3%
Circumference100.26"108.55"+8.29"+8.3%
Revolutions per mile632.0583.7−48.2−7.6%

Speedometer difference

If your vehicle came with 335/30R24 and you fit 335/40R24, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.7 mph+1.7 mph
30 mph32.5 mph+2.5 mph
40 mph43.3 mph+3.3 mph
50 mph54.1 mph+4.1 mph
60 mph65.0 mph+5.0 mph
65 mph70.4 mph+5.4 mph
70 mph75.8 mph+5.8 mph
75 mph81.2 mph+6.2 mph
80 mph86.6 mph+6.6 mph

Each size on its own

Questions

Which is bigger, 335/30R24 or 335/40R24?
335/40R24 is taller by 2.64 inches (34.55" vs 31.91"). 335/30R24 is the same width.
Can I replace 335/30R24 with 335/40R24?
It is not recommended without checking carefully. The diameter difference is +8.3%, 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 335/40R24 change my speedometer?
When your speedometer reads 60 mph with 335/40R24 fitted (calibrated for 335/30R24), your real speed is 65.0 mph. Your odometer will under-count miles by about 8.3%.
Will 335/40R24 lift my vehicle?
Ride height changes by half the diameter difference: +1.32 inches of ground clearance at the axle.

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