Tire Size Box

345/25R22 vs 325/30R22

325/30R22 compared with 345/25R22

+3.1% diameter, −0.8" width

325/30R22 is 29.68" tall vs 28.79". More than the 3% rule of thumb, so check carefully before switching.

28.8"22" rim3.4"13.6" wide
345/25R22 (solid) compared with 325/30R22 (dashed outline), drawn to scale

With 325/30R22 tires, when your speedometer says 60 mph you are really going

61.8 mph

325/30R22 is +0.89 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

345/25R22325/30R22Difference%
Overall diameter28.79"29.68"+0.89"+3.1%
Section width13.58"12.80"−0.79"−5.8%
Sidewall height3.40"3.84"+0.44"+13.0%
Circumference90.45"93.23"+2.78"+3.1%
Revolutions per mile700.5679.6−20.9−3.0%

Speedometer difference

If your vehicle came with 345/25R22 and you fit 325/30R22, 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 mph41.2 mph+1.2 mph
50 mph51.5 mph+1.5 mph
60 mph61.8 mph+1.8 mph
65 mph67.0 mph+2.0 mph
70 mph72.2 mph+2.2 mph
75 mph77.3 mph+2.3 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 345/25R22 or 325/30R22?
325/30R22 is taller by 0.89 inches (29.68" vs 28.79"). 345/25R22 is wider by 0.79 inches.
Can I replace 345/25R22 with 325/30R22?
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 325/30R22 change my speedometer?
When your speedometer reads 60 mph with 325/30R22 fitted (calibrated for 345/25R22), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.1%.
Will 325/30R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

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