Tire Size Box

325/25R19 vs 325/30R19

325/30R19 compared with 325/25R19

+5.0% diameter, 0.0" width

325/30R19 is 26.68" tall vs 25.40". More than the 3% rule of thumb, so check carefully before switching.

25.4"19" rim3.2"12.8" wide
325/25R19 (solid) compared with 325/30R19 (dashed outline), drawn to scale

With 325/30R19 tires, when your speedometer says 60 mph you are really going

63.0 mph

325/30R19 is +1.28 inches (+5.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

325/25R19325/30R19Difference%
Overall diameter25.40"26.68"+1.28"+5.0%
Section width12.80"12.80"0.00"0.0%
Sidewall height3.20"3.84"+0.64"+20.0%
Circumference79.79"83.81"+4.02"+5.0%
Revolutions per mile794.1756.0−38.1−4.8%

Speedometer difference

If your vehicle came with 325/25R19 and you fit 325/30R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.0 mph+1.0 mph
30 mph31.5 mph+1.5 mph
40 mph42.0 mph+2.0 mph
50 mph52.5 mph+2.5 mph
60 mph63.0 mph+3.0 mph
65 mph68.3 mph+3.3 mph
70 mph73.5 mph+3.5 mph
75 mph78.8 mph+3.8 mph
80 mph84.0 mph+4.0 mph

Each size on its own

Questions

Which is bigger, 325/25R19 or 325/30R19?
325/30R19 is taller by 1.28 inches (26.68" vs 25.40"). 325/25R19 is the same width.
Can I replace 325/25R19 with 325/30R19?
It is not recommended without checking carefully. The diameter difference is +5.0%, 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 325/30R19 change my speedometer?
When your speedometer reads 60 mph with 325/30R19 fitted (calibrated for 325/25R19), your real speed is 63.0 mph. Your odometer will under-count miles by about 5.0%.
Will 325/30R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.64 inches of ground clearance at the axle.

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