Tire Size Box

335/25R20 vs 325/30R20

325/30R20 compared with 335/25R20

+4.1% diameter, −0.4" width

325/30R20 is 27.68" tall vs 26.59". More than the 3% rule of thumb, so check carefully before switching.

26.6"20" rim3.3"13.2" wide
335/25R20 (solid) compared with 325/30R20 (dashed outline), drawn to scale

With 325/30R20 tires, when your speedometer says 60 mph you are really going

62.4 mph

325/30R20 is +1.08 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/25R20325/30R20Difference%
Overall diameter26.59"27.68"+1.08"+4.1%
Section width13.19"12.80"−0.39"−3.0%
Sidewall height3.30"3.84"+0.54"+16.4%
Circumference83.55"86.95"+3.40"+4.1%
Revolutions per mile758.4728.7−29.7−3.9%

Speedometer difference

If your vehicle came with 335/25R20 and you fit 325/30R20, 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 mph78.1 mph+3.1 mph
80 mph83.3 mph+3.3 mph

Each size on its own

Questions

Which is bigger, 335/25R20 or 325/30R20?
325/30R20 is taller by 1.08 inches (27.68" vs 26.59"). 335/25R20 is wider by 0.39 inches.
Can I replace 335/25R20 with 325/30R20?
It is not recommended without checking carefully. The diameter difference is +4.1%, 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 325/30R20 change my speedometer?
When your speedometer reads 60 mph with 325/30R20 fitted (calibrated for 335/25R20), your real speed is 62.4 mph. Your odometer will under-count miles by about 4.1%.
Will 325/30R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.54 inches of ground clearance at the axle.

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