Tire Size Box

245/60R20 vs 245/65R20

245/65R20 compared with 245/60R20

+3.1% diameter, 0.0" width

245/65R20 is 32.54" tall vs 31.57". More than the 3% rule of thumb, so check carefully before switching.

31.6"20" rim5.8"9.6" wide
245/60R20 (solid) compared with 245/65R20 (dashed outline), drawn to scale

With 245/65R20 tires, when your speedometer says 60 mph you are really going

61.8 mph

245/65R20 is +0.96 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/60R20245/65R20Difference%
Overall diameter31.57"32.54"+0.96"+3.1%
Section width9.65"9.65"0.00"0.0%
Sidewall height5.79"6.27"+0.48"+8.3%
Circumference99.20"102.23"+3.03"+3.1%
Revolutions per mile638.7619.8−18.9−3.0%

Speedometer difference

If your vehicle came with 245/60R20 and you fit 245/65R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.2 mph+1.2 mph
50 mph51.5 mph+1.5 mph
60 mph61.8 mph+1.8 mph
65 mph67.0 mph+2.0 mph
70 mph72.1 mph+2.1 mph
75 mph77.3 mph+2.3 mph
80 mph82.4 mph+2.4 mph

Each size on its own

Questions

Which is bigger, 245/60R20 or 245/65R20?
245/65R20 is taller by 0.96 inches (32.54" vs 31.57"). 245/60R20 is the same width.
Can I replace 245/60R20 with 245/65R20?
It is not recommended without checking carefully. The diameter difference is +3.1%, 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 245/65R20 change my speedometer?
When your speedometer reads 60 mph with 245/65R20 fitted (calibrated for 245/60R20), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.1%.
Will 245/65R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.48 inches of ground clearance at the axle.

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