Tire Size Box

265/30R19 vs 265/40R19

265/40R19 compared with 265/30R19

+8.3% diameter, 0.0" width

265/40R19 is 27.35" tall vs 25.26". More than the 3% rule of thumb, so check carefully before switching.

25.3"19" rim3.1"10.4" wide
265/30R19 (solid) compared with 265/40R19 (dashed outline), drawn to scale

With 265/40R19 tires, when your speedometer says 60 mph you are really going

65.0 mph

265/40R19 is +2.09 inches (+8.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/30R19265/40R19Difference%
Overall diameter25.26"27.35"+2.09"+8.3%
Section width10.43"10.43"0.00"0.0%
Sidewall height3.13"4.17"+1.04"+33.3%
Circumference79.36"85.91"+6.56"+8.3%
Revolutions per mile798.4737.5−60.9−7.6%

Speedometer difference

If your vehicle came with 265/30R19 and you fit 265/40R19, 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, 265/30R19 or 265/40R19?
265/40R19 is taller by 2.09 inches (27.35" vs 25.26"). 265/30R19 is the same width.
Can I replace 265/30R19 with 265/40R19?
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 265/40R19 change my speedometer?
When your speedometer reads 60 mph with 265/40R19 fitted (calibrated for 265/30R19), your real speed is 65.0 mph. Your odometer will under-count miles by about 8.3%.
Will 265/40R19 lift my vehicle?
Ride height changes by half the diameter difference: +1.04 inches of ground clearance at the axle.

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