Tire Size Box

245/25R20 vs 245/35R20

245/35R20 compared with 245/25R20

+7.8% diameter, 0.0" width

245/35R20 is 26.75" tall vs 24.82". More than the 3% rule of thumb, so check carefully before switching.

24.8"20" rim2.4"9.6" wide
245/25R20 (solid) compared with 245/35R20 (dashed outline), drawn to scale

With 245/35R20 tires, when your speedometer says 60 mph you are really going

64.7 mph

245/35R20 is +1.93 inches (+7.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/25R20245/35R20Difference%
Overall diameter24.82"26.75"+1.93"+7.8%
Section width9.65"9.65"0.00"0.0%
Sidewall height2.41"3.38"+0.96"+40.0%
Circumference77.98"84.04"+6.06"+7.8%
Revolutions per mile812.5753.9−58.6−7.2%

Speedometer difference

If your vehicle came with 245/25R20 and you fit 245/35R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.3 mph+2.3 mph
40 mph43.1 mph+3.1 mph
50 mph53.9 mph+3.9 mph
60 mph64.7 mph+4.7 mph
65 mph70.1 mph+5.1 mph
70 mph75.4 mph+5.4 mph
75 mph80.8 mph+5.8 mph
80 mph86.2 mph+6.2 mph

Each size on its own

Questions

Which is bigger, 245/25R20 or 245/35R20?
245/35R20 is taller by 1.93 inches (26.75" vs 24.82"). 245/25R20 is the same width.
Can I replace 245/25R20 with 245/35R20?
It is not recommended without checking carefully. The diameter difference is +7.8%, 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 245/35R20 change my speedometer?
When your speedometer reads 60 mph with 245/35R20 fitted (calibrated for 245/25R20), your real speed is 64.7 mph. Your odometer will under-count miles by about 7.8%.
Will 245/35R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.96 inches of ground clearance at the axle.

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