Tire Size Box

355/30R22 vs 355/40R22

355/40R22 compared with 355/30R22

+9.2% diameter, 0.0" width

355/40R22 is 33.18" tall vs 30.39". More than the 3% rule of thumb, so check carefully before switching.

30.4"22" rim4.2"14.0" wide
355/30R22 (solid) compared with 355/40R22 (dashed outline), drawn to scale

With 355/40R22 tires, when your speedometer says 60 mph you are really going

65.5 mph

355/40R22 is +2.80 inches (+9.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/30R22355/40R22Difference%
Overall diameter30.39"33.18"+2.80"+9.2%
Section width13.98"13.98"0.00"0.0%
Sidewall height4.19"5.59"+1.40"+33.3%
Circumference95.46"104.24"+8.78"+9.2%
Revolutions per mile663.7607.8−55.9−8.4%

Speedometer difference

If your vehicle came with 355/30R22 and you fit 355/40R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.8 mph+1.8 mph
30 mph32.8 mph+2.8 mph
40 mph43.7 mph+3.7 mph
50 mph54.6 mph+4.6 mph
60 mph65.5 mph+5.5 mph
65 mph71.0 mph+6.0 mph
70 mph76.4 mph+6.4 mph
75 mph81.9 mph+6.9 mph
80 mph87.4 mph+7.4 mph

Each size on its own

Questions

Which is bigger, 355/30R22 or 355/40R22?
355/40R22 is taller by 2.80 inches (33.18" vs 30.39"). 355/30R22 is the same width.
Can I replace 355/30R22 with 355/40R22?
It is not recommended without checking carefully. The diameter difference is +9.2%, 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 355/40R22 change my speedometer?
When your speedometer reads 60 mph with 355/40R22 fitted (calibrated for 355/30R22), your real speed is 65.5 mph. Your odometer will under-count miles by about 9.2%.
Will 355/40R22 lift my vehicle?
Ride height changes by half the diameter difference: +1.40 inches of ground clearance at the axle.

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