Tire Size Box

235/55R20 vs 235/60R20

235/60R20 compared with 235/55R20

+3.1% diameter, 0.0" width

235/60R20 is 31.10" tall vs 30.18". More than the 3% rule of thumb, so check carefully before switching.

30.2"20" rim5.1"9.3" wide
235/55R20 (solid) compared with 235/60R20 (dashed outline), drawn to scale

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

61.8 mph

235/60R20 is +0.93 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/55R20235/60R20Difference%
Overall diameter30.18"31.10"+0.93"+3.1%
Section width9.25"9.25"0.00"0.0%
Sidewall height5.09"5.55"+0.46"+9.1%
Circumference94.80"97.71"+2.91"+3.1%
Revolutions per mile668.3648.4−19.9−3.0%

Speedometer difference

If your vehicle came with 235/55R20 and you fit 235/60R20, 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 mph41.2 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 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 235/55R20 or 235/60R20?
235/60R20 is taller by 0.93 inches (31.10" vs 30.18"). 235/55R20 is the same width.
Can I replace 235/55R20 with 235/60R20?
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 235/60R20 change my speedometer?
When your speedometer reads 60 mph with 235/60R20 fitted (calibrated for 235/55R20), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.1%.
Will 235/60R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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