Tire Size Box

255/50R16 vs 255/55R16

255/55R16 compared with 255/50R16

+3.9% diameter, 0.0" width

255/55R16 is 27.04" tall vs 26.04". More than the 3% rule of thumb, so check carefully before switching.

26.0"16" rim5.0"10.0" wide
255/50R16 (solid) compared with 255/55R16 (dashed outline), drawn to scale

With 255/55R16 tires, when your speedometer says 60 mph you are really going

62.3 mph

255/55R16 is +1.00 inches (+3.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

255/50R16255/55R16Difference%
Overall diameter26.04"27.04"+1.00"+3.9%
Section width10.04"10.04"0.00"0.0%
Sidewall height5.02"5.52"+0.50"+10.0%
Circumference81.81"84.96"+3.15"+3.9%
Revolutions per mile774.5745.8−28.8−3.7%

Speedometer difference

If your vehicle came with 255/50R16 and you fit 255/55R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.9 mph+2.9 mph
80 mph83.1 mph+3.1 mph

Each size on its own

Questions

Which is bigger, 255/50R16 or 255/55R16?
255/55R16 is taller by 1.00 inches (27.04" vs 26.04"). 255/50R16 is the same width.
Can I replace 255/50R16 with 255/55R16?
It is not recommended without checking carefully. The diameter difference is +3.9%, 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 255/55R16 change my speedometer?
When your speedometer reads 60 mph with 255/55R16 fitted (calibrated for 255/50R16), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.9%.
Will 255/55R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.50 inches of ground clearance at the axle.

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