Tire Size Box

265/50R20 vs 265/55R20

265/55R20 compared with 265/50R20

+3.4% diameter, 0.0" width

265/55R20 is 31.48" tall vs 30.43". More than the 3% rule of thumb, so check carefully before switching.

30.4"20" rim5.2"10.4" wide
265/50R20 (solid) compared with 265/55R20 (dashed outline), drawn to scale

With 265/55R20 tires, when your speedometer says 60 mph you are really going

62.1 mph

265/55R20 is +1.04 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/50R20265/55R20Difference%
Overall diameter30.43"31.48"+1.04"+3.4%
Section width10.43"10.43"0.00"0.0%
Sidewall height5.22"5.74"+0.52"+10.0%
Circumference95.61"98.89"+3.28"+3.4%
Revolutions per mile662.7640.7−22.0−3.3%

Speedometer difference

If your vehicle came with 265/50R20 and you fit 265/55R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 265/50R20 or 265/55R20?
265/55R20 is taller by 1.04 inches (31.48" vs 30.43"). 265/50R20 is the same width.
Can I replace 265/50R20 with 265/55R20?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 265/55R20 change my speedometer?
When your speedometer reads 60 mph with 265/55R20 fitted (calibrated for 265/50R20), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.4%.
Will 265/55R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.52 inches of ground clearance at the axle.

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