Tire Size Box

325/25R20 vs 325/35R20

325/35R20 compared with 325/25R20

+9.7% diameter, 0.0" width

325/35R20 is 28.96" tall vs 26.40". More than the 3% rule of thumb, so check carefully before switching.

26.4"20" rim3.2"12.8" wide
325/25R20 (solid) compared with 325/35R20 (dashed outline), drawn to scale

With 325/35R20 tires, when your speedometer says 60 mph you are really going

65.8 mph

325/35R20 is +2.56 inches (+9.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

325/25R20325/35R20Difference%
Overall diameter26.40"28.96"+2.56"+9.7%
Section width12.80"12.80"0.00"0.0%
Sidewall height3.20"4.48"+1.28"+40.0%
Circumference82.93"90.97"+8.04"+9.7%
Revolutions per mile764.0696.5−67.5−8.8%

Speedometer difference

If your vehicle came with 325/25R20 and you fit 325/35R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.9 mph+1.9 mph
30 mph32.9 mph+2.9 mph
40 mph43.9 mph+3.9 mph
50 mph54.8 mph+4.8 mph
60 mph65.8 mph+5.8 mph
65 mph71.3 mph+6.3 mph
70 mph76.8 mph+6.8 mph
75 mph82.3 mph+7.3 mph
80 mph87.8 mph+7.8 mph

Each size on its own

Questions

Which is bigger, 325/25R20 or 325/35R20?
325/35R20 is taller by 2.56 inches (28.96" vs 26.40"). 325/25R20 is the same width.
Can I replace 325/25R20 with 325/35R20?
It is not recommended without checking carefully. The diameter difference is +9.7%, 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 325/35R20 change my speedometer?
When your speedometer reads 60 mph with 325/35R20 fitted (calibrated for 325/25R20), your real speed is 65.8 mph. Your odometer will under-count miles by about 9.7%.
Will 325/35R20 lift my vehicle?
Ride height changes by half the diameter difference: +1.28 inches of ground clearance at the axle.

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