Tire Size Box

335/25R20 vs 335/30R20

335/30R20 compared with 335/25R20

+5.0% diameter, 0.0" width

335/30R20 is 27.91" 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 335/30R20 (dashed outline), drawn to scale

With 335/30R20 tires, when your speedometer says 60 mph you are really going

63.0 mph

335/30R20 is +1.32 inches (+5.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/25R20335/30R20Difference%
Overall diameter26.59"27.91"+1.32"+5.0%
Section width13.19"13.19"0.00"0.0%
Sidewall height3.30"3.96"+0.66"+20.0%
Circumference83.55"87.69"+4.14"+5.0%
Revolutions per mile758.4722.5−35.8−4.7%

Speedometer difference

If your vehicle came with 335/25R20 and you fit 335/30R20, 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 mph68.2 mph+3.2 mph
70 mph73.5 mph+3.5 mph
75 mph78.7 mph+3.7 mph
80 mph84.0 mph+4.0 mph

Each size on its own

Questions

Which is bigger, 335/25R20 or 335/30R20?
335/30R20 is taller by 1.32 inches (27.91" vs 26.59"). 335/25R20 is the same width.
Can I replace 335/25R20 with 335/30R20?
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 335/30R20 change my speedometer?
When your speedometer reads 60 mph with 335/30R20 fitted (calibrated for 335/25R20), your real speed is 63.0 mph. Your odometer will under-count miles by about 5.0%.
Will 335/30R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.66 inches of ground clearance at the axle.

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