Tire Size Box

255/75R17 vs 275/75R17

275/75R17 compared with 255/75R17

+3.7% diameter, +0.8" width

275/75R17 is 33.24" tall vs 32.06". More than the 3% rule of thumb, so check carefully before switching.

32.1"17" rim7.5"10.0" wide
255/75R17 (solid) compared with 275/75R17 (dashed outline), drawn to scale

With 275/75R17 tires, when your speedometer says 60 mph you are really going

62.2 mph

275/75R17 is +1.18 inches (+3.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

255/75R17275/75R17Difference%
Overall diameter32.06"33.24"+1.18"+3.7%
Section width10.04"10.83"+0.79"+7.8%
Sidewall height7.53"8.12"+0.59"+7.8%
Circumference100.72"104.43"+3.71"+3.7%
Revolutions per mile629.1606.7−22.4−3.6%

Speedometer difference

If your vehicle came with 255/75R17 and you fit 275/75R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.8 mph+1.8 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.6 mph+2.6 mph
75 mph77.8 mph+2.8 mph
80 mph82.9 mph+2.9 mph

Each size on its own

Questions

Which is bigger, 255/75R17 or 275/75R17?
275/75R17 is taller by 1.18 inches (33.24" vs 32.06"). 275/75R17 is wider by 0.79 inches.
Can I replace 255/75R17 with 275/75R17?
It is not recommended without checking carefully. The diameter difference is +3.7%, 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 275/75R17 change my speedometer?
When your speedometer reads 60 mph with 275/75R17 fitted (calibrated for 255/75R17), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.7%.
Will 275/75R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.59 inches of ground clearance at the axle.

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