Tire Size Box

345/25R20 vs 335/30R20

335/30R20 compared with 345/25R20

+4.2% diameter, −0.4" width

335/30R20 is 27.91" tall vs 26.79". More than the 3% rule of thumb, so check carefully before switching.

26.8"20" rim3.4"13.6" wide
345/25R20 (solid) compared with 335/30R20 (dashed outline), drawn to scale

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

62.5 mph

335/30R20 is +1.12 inches (+4.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

345/25R20335/30R20Difference%
Overall diameter26.79"27.91"+1.12"+4.2%
Section width13.58"13.19"−0.39"−2.9%
Sidewall height3.40"3.96"+0.56"+16.5%
Circumference84.17"87.69"+3.53"+4.2%
Revolutions per mile752.8722.5−30.3−4.0%

Speedometer difference

If your vehicle came with 345/25R20 and you fit 335/30R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.3 mph+1.3 mph
40 mph41.7 mph+1.7 mph
50 mph52.1 mph+2.1 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 mph
70 mph72.9 mph+2.9 mph
75 mph78.1 mph+3.1 mph
80 mph83.4 mph+3.4 mph

Each size on its own

Questions

Which is bigger, 345/25R20 or 335/30R20?
335/30R20 is taller by 1.12 inches (27.91" vs 26.79"). 345/25R20 is wider by 0.39 inches.
Can I replace 345/25R20 with 335/30R20?
It is not recommended without checking carefully. The diameter difference is +4.2%, 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 345/25R20), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.2%.
Will 335/30R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.56 inches of ground clearance at the axle.

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