Tire Size Box

265/30R24 vs 265/40R24

265/40R24 compared with 265/30R24

+6.9% diameter, 0.0" width

265/40R24 is 32.35" tall vs 30.26". More than the 3% rule of thumb, so check carefully before switching.

30.3"24" rim3.1"10.4" wide
265/30R24 (solid) compared with 265/40R24 (dashed outline), drawn to scale

With 265/40R24 tires, when your speedometer says 60 mph you are really going

64.1 mph

265/40R24 is +2.09 inches (+6.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/30R24265/40R24Difference%
Overall diameter30.26"32.35"+2.09"+6.9%
Section width10.43"10.43"0.00"0.0%
Sidewall height3.13"4.17"+1.04"+33.3%
Circumference95.06"101.62"+6.56"+6.9%
Revolutions per mile666.5623.5−43.0−6.5%

Speedometer difference

If your vehicle came with 265/30R24 and you fit 265/40R24, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.4 mph+1.4 mph
30 mph32.1 mph+2.1 mph
40 mph42.8 mph+2.8 mph
50 mph53.4 mph+3.4 mph
60 mph64.1 mph+4.1 mph
65 mph69.5 mph+4.5 mph
70 mph74.8 mph+4.8 mph
75 mph80.2 mph+5.2 mph
80 mph85.5 mph+5.5 mph

Each size on its own

Questions

Which is bigger, 265/30R24 or 265/40R24?
265/40R24 is taller by 2.09 inches (32.35" vs 30.26"). 265/30R24 is the same width.
Can I replace 265/30R24 with 265/40R24?
It is not recommended without checking carefully. The diameter difference is +6.9%, 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 265/40R24 change my speedometer?
When your speedometer reads 60 mph with 265/40R24 fitted (calibrated for 265/30R24), your real speed is 64.1 mph. Your odometer will under-count miles by about 6.9%.
Will 265/40R24 lift my vehicle?
Ride height changes by half the diameter difference: +1.04 inches of ground clearance at the axle.

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