Tire Size Box

245/55R20 vs 245/60R20

245/60R20 compared with 245/55R20

+3.2% diameter, 0.0" width

245/60R20 is 31.57" tall vs 30.61". More than the 3% rule of thumb, so check carefully before switching.

30.6"20" rim5.3"9.6" wide
245/55R20 (solid) compared with 245/60R20 (dashed outline), drawn to scale

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

61.9 mph

245/60R20 is +0.96 inches (+3.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/55R20245/60R20Difference%
Overall diameter30.61"31.57"+0.96"+3.2%
Section width9.65"9.65"0.00"0.0%
Sidewall height5.31"5.79"+0.48"+9.1%
Circumference96.16"99.20"+3.03"+3.2%
Revolutions per mile658.9638.7−20.1−3.1%

Speedometer difference

If your vehicle came with 245/55R20 and you fit 245/60R20, 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 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.0 mph+2.0 mph
70 mph72.2 mph+2.2 mph
75 mph77.4 mph+2.4 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 245/55R20 or 245/60R20?
245/60R20 is taller by 0.96 inches (31.57" vs 30.61"). 245/55R20 is the same width.
Can I replace 245/55R20 with 245/60R20?
It is not recommended without checking carefully. The diameter difference is +3.2%, 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 245/60R20 change my speedometer?
When your speedometer reads 60 mph with 245/60R20 fitted (calibrated for 245/55R20), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.2%.
Will 245/60R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.48 inches of ground clearance at the axle.

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