Tire Size Box

255/55R17 vs 275/55R17

275/55R17 compared with 255/55R17

+3.1% diameter, +0.8" width

275/55R17 is 28.91" tall vs 28.04". More than the 3% rule of thumb, so check carefully before switching.

28.0"17" rim5.5"10.0" wide
255/55R17 (solid) compared with 275/55R17 (dashed outline), drawn to scale

With 275/55R17 tires, when your speedometer says 60 mph you are really going

61.9 mph

275/55R17 is +0.87 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

255/55R17275/55R17Difference%
Overall diameter28.04"28.91"+0.87"+3.1%
Section width10.04"10.83"+0.79"+7.8%
Sidewall height5.52"5.95"+0.43"+7.8%
Circumference88.10"90.82"+2.72"+3.1%
Revolutions per mile719.2697.6−21.5−3.0%

Speedometer difference

If your vehicle came with 255/55R17 and you fit 275/55R17, 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 mph61.9 mph+1.9 mph
65 mph67.0 mph+2.0 mph
70 mph72.2 mph+2.2 mph
75 mph77.3 mph+2.3 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 255/55R17 or 275/55R17?
275/55R17 is taller by 0.87 inches (28.91" vs 28.04"). 275/55R17 is wider by 0.79 inches.
Can I replace 255/55R17 with 275/55R17?
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 275/55R17 change my speedometer?
When your speedometer reads 60 mph with 275/55R17 fitted (calibrated for 255/55R17), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.1%.
Will 275/55R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.43 inches of ground clearance at the axle.

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