Tire Size Box

355/25R20 vs 355/35R20

355/35R20 compared with 355/25R20

+10.4% diameter, 0.0" width

355/35R20 is 29.78" 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 355/35R20 (dashed outline), drawn to scale

With 355/35R20 tires, when your speedometer says 60 mph you are really going

66.2 mph

355/35R20 is +2.80 inches (+10.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/25R20355/35R20Difference%
Overall diameter26.99"29.78"+2.80"+10.4%
Section width13.98"13.98"0.00"0.0%
Sidewall height3.49"4.89"+1.40"+40.0%
Circumference84.79"93.57"+8.78"+10.4%
Revolutions per mile747.3677.2−70.1−9.4%

Speedometer difference

If your vehicle came with 355/25R20 and you fit 355/35R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph22.1 mph+2.1 mph
30 mph33.1 mph+3.1 mph
40 mph44.1 mph+4.1 mph
50 mph55.2 mph+5.2 mph
60 mph66.2 mph+6.2 mph
65 mph71.7 mph+6.7 mph
70 mph77.3 mph+7.3 mph
75 mph82.8 mph+7.8 mph
80 mph88.3 mph+8.3 mph

Each size on its own

Questions

Which is bigger, 355/25R20 or 355/35R20?
355/35R20 is taller by 2.80 inches (29.78" vs 26.99"). 355/25R20 is the same width.
Can I replace 355/25R20 with 355/35R20?
It is not recommended without checking carefully. The diameter difference is +10.4%, 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 355/35R20 change my speedometer?
When your speedometer reads 60 mph with 355/35R20 fitted (calibrated for 355/25R20), your real speed is 66.2 mph. Your odometer will under-count miles by about 10.4%.
Will 355/35R20 lift my vehicle?
Ride height changes by half the diameter difference: +1.40 inches of ground clearance at the axle.

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