Tire Size Box

235/25R20 vs 235/35R20

235/35R20 compared with 235/25R20

+7.5% diameter, 0.0" width

235/35R20 is 26.48" tall vs 24.63". More than the 3% rule of thumb, so check carefully before switching.

24.6"20" rim2.3"9.3" wide
235/25R20 (solid) compared with 235/35R20 (dashed outline), drawn to scale

With 235/35R20 tires, when your speedometer says 60 mph you are really going

64.5 mph

235/35R20 is +1.85 inches (+7.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/25R20235/35R20Difference%
Overall diameter24.63"26.48"+1.85"+7.5%
Section width9.25"9.25"0.00"0.0%
Sidewall height2.31"3.24"+0.93"+40.0%
Circumference77.36"83.18"+5.81"+7.5%
Revolutions per mile819.0761.7−57.2−7.0%

Speedometer difference

If your vehicle came with 235/25R20 and you fit 235/35R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.5 mph+1.5 mph
30 mph32.3 mph+2.3 mph
40 mph43.0 mph+3.0 mph
50 mph53.8 mph+3.8 mph
60 mph64.5 mph+4.5 mph
65 mph69.9 mph+4.9 mph
70 mph75.3 mph+5.3 mph
75 mph80.6 mph+5.6 mph
80 mph86.0 mph+6.0 mph

Each size on its own

Questions

Which is bigger, 235/25R20 or 235/35R20?
235/35R20 is taller by 1.85 inches (26.48" vs 24.63"). 235/25R20 is the same width.
Can I replace 235/25R20 with 235/35R20?
It is not recommended without checking carefully. The diameter difference is +7.5%, 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 235/35R20 change my speedometer?
When your speedometer reads 60 mph with 235/35R20 fitted (calibrated for 235/25R20), your real speed is 64.5 mph. Your odometer will under-count miles by about 7.5%.
Will 235/35R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

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