Tire Size Box

335/30R19 vs 335/40R19

335/40R19 compared with 335/30R19

+9.8% diameter, 0.0" width

335/40R19 is 29.55" tall vs 26.91". More than the 3% rule of thumb, so check carefully before switching.

26.9"19" rim4.0"13.2" wide
335/30R19 (solid) compared with 335/40R19 (dashed outline), drawn to scale

With 335/40R19 tires, when your speedometer says 60 mph you are really going

65.9 mph

335/40R19 is +2.64 inches (+9.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/30R19335/40R19Difference%
Overall diameter26.91"29.55"+2.64"+9.8%
Section width13.19"13.19"0.00"0.0%
Sidewall height3.96"5.28"+1.32"+33.3%
Circumference84.55"92.84"+8.29"+9.8%
Revolutions per mile749.4682.5−66.9−8.9%

Speedometer difference

If your vehicle came with 335/30R19 and you fit 335/40R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph22.0 mph+2.0 mph
30 mph32.9 mph+2.9 mph
40 mph43.9 mph+3.9 mph
50 mph54.9 mph+4.9 mph
60 mph65.9 mph+5.9 mph
65 mph71.4 mph+6.4 mph
70 mph76.9 mph+6.9 mph
75 mph82.4 mph+7.4 mph
80 mph87.8 mph+7.8 mph

Each size on its own

Questions

Which is bigger, 335/30R19 or 335/40R19?
335/40R19 is taller by 2.64 inches (29.55" vs 26.91"). 335/30R19 is the same width.
Can I replace 335/30R19 with 335/40R19?
It is not recommended without checking carefully. The diameter difference is +9.8%, 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 335/40R19 change my speedometer?
When your speedometer reads 60 mph with 335/40R19 fitted (calibrated for 335/30R19), your real speed is 65.9 mph. Your odometer will under-count miles by about 9.8%.
Will 335/40R19 lift my vehicle?
Ride height changes by half the diameter difference: +1.32 inches of ground clearance at the axle.

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