Tire Size Box

355/25R20 vs 335/30R20

335/30R20 compared with 355/25R20

+3.4% diameter, −0.8" width

335/30R20 is 27.91" tall vs 26.99". More than the 3% rule of thumb, so check carefully before switching.

27.0"20" rim3.5"14.0" wide
355/25R20 (solid) compared with 335/30R20 (dashed outline), drawn to scale

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

62.1 mph

335/30R20 is +0.93 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/25R20335/30R20Difference%
Overall diameter26.99"27.91"+0.93"+3.4%
Section width13.98"13.19"−0.79"−5.6%
Sidewall height3.49"3.96"+0.46"+13.2%
Circumference84.79"87.69"+2.91"+3.4%
Revolutions per mile747.3722.5−24.8−3.3%

Speedometer difference

If your vehicle came with 355/25R20 and you fit 335/30R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 355/25R20 or 335/30R20?
335/30R20 is taller by 0.93 inches (27.91" vs 26.99"). 355/25R20 is wider by 0.79 inches.
Can I replace 355/25R20 with 335/30R20?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 355/25R20), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.4%.
Will 335/30R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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