Tire Size Box

355/40R22 vs 355/45R22

355/45R22 compared with 355/40R22

+4.2% diameter, 0.0" width

355/45R22 is 34.58" tall vs 33.18". More than the 3% rule of thumb, so check carefully before switching.

33.2"22" rim5.6"14.0" wide
355/40R22 (solid) compared with 355/45R22 (dashed outline), drawn to scale

With 355/45R22 tires, when your speedometer says 60 mph you are really going

62.5 mph

355/45R22 is +1.40 inches (+4.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/40R22355/45R22Difference%
Overall diameter33.18"34.58"+1.40"+4.2%
Section width13.98"13.98"0.00"0.0%
Sidewall height5.59"6.29"+0.70"+12.5%
Circumference104.24"108.63"+4.39"+4.2%
Revolutions per mile607.8583.3−24.6−4.0%

Speedometer difference

If your vehicle came with 355/40R22 and you fit 355/45R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.3 mph+1.3 mph
40 mph41.7 mph+1.7 mph
50 mph52.1 mph+2.1 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 mph
70 mph72.9 mph+2.9 mph
75 mph78.2 mph+3.2 mph
80 mph83.4 mph+3.4 mph

Each size on its own

Questions

Which is bigger, 355/40R22 or 355/45R22?
355/45R22 is taller by 1.40 inches (34.58" vs 33.18"). 355/40R22 is the same width.
Can I replace 355/40R22 with 355/45R22?
It is not recommended without checking carefully. The diameter difference is +4.2%, 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 355/45R22 change my speedometer?
When your speedometer reads 60 mph with 355/45R22 fitted (calibrated for 355/40R22), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.2%.
Will 355/45R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.70 inches of ground clearance at the axle.

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