Tire Size Box

235/55R16 vs 255/55R16

255/55R16 compared with 235/55R16

+3.3% diameter, +0.8" width

255/55R16 is 27.04" tall vs 26.18". More than the 3% rule of thumb, so check carefully before switching.

26.2"16" rim5.1"9.3" wide
235/55R16 (solid) compared with 255/55R16 (dashed outline), drawn to scale

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

62.0 mph

255/55R16 is +0.87 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/55R16255/55R16Difference%
Overall diameter26.18"27.04"+0.87"+3.3%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height5.09"5.52"+0.43"+8.5%
Circumference82.24"84.96"+2.72"+3.3%
Revolutions per mile770.4745.8−24.7−3.2%

Speedometer difference

If your vehicle came with 235/55R16 and you fit 255/55R16, 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 mph41.3 mph+1.3 mph
50 mph51.7 mph+1.7 mph
60 mph62.0 mph+2.0 mph
65 mph67.2 mph+2.2 mph
70 mph72.3 mph+2.3 mph
75 mph77.5 mph+2.5 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 235/55R16 or 255/55R16?
255/55R16 is taller by 0.87 inches (27.04" vs 26.18"). 255/55R16 is wider by 0.79 inches.
Can I replace 235/55R16 with 255/55R16?
It is not recommended without checking carefully. The diameter difference is +3.3%, 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 235/55R16), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 255/55R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.43 inches of ground clearance at the axle.

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