Tire Size Box

355/40R22 vs 345/45R22

345/45R22 compared with 355/40R22

+3.1% diameter, −0.4" width

345/45R22 is 34.22" 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 345/45R22 (dashed outline), drawn to scale

With 345/45R22 tires, when your speedometer says 60 mph you are really going

61.9 mph

345/45R22 is +1.04 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/40R22345/45R22Difference%
Overall diameter33.18"34.22"+1.04"+3.1%
Section width13.98"13.58"−0.39"−2.8%
Sidewall height5.59"6.11"+0.52"+9.3%
Circumference104.24"107.52"+3.28"+3.1%
Revolutions per mile607.8589.3−18.5−3.0%

Speedometer difference

If your vehicle came with 355/40R22 and you fit 345/45R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.0 mph+2.0 mph
70 mph72.2 mph+2.2 mph
75 mph77.4 mph+2.4 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 355/40R22 or 345/45R22?
345/45R22 is taller by 1.04 inches (34.22" vs 33.18"). 355/40R22 is wider by 0.39 inches.
Can I replace 355/40R22 with 345/45R22?
It is not recommended without checking carefully. The diameter difference is +3.1%, 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 345/45R22 change my speedometer?
When your speedometer reads 60 mph with 345/45R22 fitted (calibrated for 355/40R22), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.1%.
Will 345/45R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.52 inches of ground clearance at the axle.

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