Tire Size Box

325/25R22 vs 325/30R22

325/30R22 compared with 325/25R22

+4.5% diameter, 0.0" width

325/30R22 is 29.68" tall vs 28.40". More than the 3% rule of thumb, so check carefully before switching.

28.4"22" rim3.2"12.8" wide
325/25R22 (solid) compared with 325/30R22 (dashed outline), drawn to scale

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

62.7 mph

325/30R22 is +1.28 inches (+4.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

325/25R22325/30R22Difference%
Overall diameter28.40"29.68"+1.28"+4.5%
Section width12.80"12.80"0.00"0.0%
Sidewall height3.20"3.84"+0.64"+20.0%
Circumference89.21"93.23"+4.02"+4.5%
Revolutions per mile710.2679.6−30.6−4.3%

Speedometer difference

If your vehicle came with 325/25R22 and you fit 325/30R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.9 mph+0.9 mph
30 mph31.4 mph+1.4 mph
40 mph41.8 mph+1.8 mph
50 mph52.3 mph+2.3 mph
60 mph62.7 mph+2.7 mph
65 mph67.9 mph+2.9 mph
70 mph73.2 mph+3.2 mph
75 mph78.4 mph+3.4 mph
80 mph83.6 mph+3.6 mph

Each size on its own

Questions

Which is bigger, 325/25R22 or 325/30R22?
325/30R22 is taller by 1.28 inches (29.68" vs 28.40"). 325/25R22 is the same width.
Can I replace 325/25R22 with 325/30R22?
It is not recommended without checking carefully. The diameter difference is +4.5%, 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 325/25R22), your real speed is 62.7 mph. Your odometer will under-count miles by about 4.5%.
Will 325/30R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.64 inches of ground clearance at the axle.

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