Tire Size Box

355/25R22 vs 345/30R22

345/30R22 compared with 355/25R22

+4.0% diameter, −0.4" width

345/30R22 is 30.15" tall vs 28.99". More than the 3% rule of thumb, so check carefully before switching.

29.0"22" rim3.5"14.0" wide
355/25R22 (solid) compared with 345/30R22 (dashed outline), drawn to scale

With 345/30R22 tires, when your speedometer says 60 mph you are really going

62.4 mph

345/30R22 is +1.16 inches (+4.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/25R22345/30R22Difference%
Overall diameter28.99"30.15"+1.16"+4.0%
Section width13.98"13.58"−0.39"−2.8%
Sidewall height3.49"4.07"+0.58"+16.6%
Circumference91.07"94.72"+3.65"+4.0%
Revolutions per mile695.7668.9−26.8−3.9%

Speedometer difference

If your vehicle came with 355/25R22 and you fit 345/30R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.6 mph+1.6 mph
50 mph52.0 mph+2.0 mph
60 mph62.4 mph+2.4 mph
65 mph67.6 mph+2.6 mph
70 mph72.8 mph+2.8 mph
75 mph78.0 mph+3.0 mph
80 mph83.2 mph+3.2 mph

Each size on its own

Questions

Which is bigger, 355/25R22 or 345/30R22?
345/30R22 is taller by 1.16 inches (30.15" vs 28.99"). 355/25R22 is wider by 0.39 inches.
Can I replace 355/25R22 with 345/30R22?
It is not recommended without checking carefully. The diameter difference is +4.0%, 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 345/30R22 change my speedometer?
When your speedometer reads 60 mph with 345/30R22 fitted (calibrated for 355/25R22), your real speed is 62.4 mph. Your odometer will under-count miles by about 4.0%.
Will 345/30R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.58 inches of ground clearance at the axle.

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