Tire Size Box

255/60R17 vs 275/60R17

275/60R17 compared with 255/60R17

+3.3% diameter, +0.8" width

275/60R17 is 29.99" tall vs 29.05". More than the 3% rule of thumb, so check carefully before switching.

29.0"17" rim6.0"10.0" wide
255/60R17 (solid) compared with 275/60R17 (dashed outline), drawn to scale

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

62.0 mph

275/60R17 is +0.94 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

255/60R17275/60R17Difference%
Overall diameter29.05"29.99"+0.94"+3.3%
Section width10.04"10.83"+0.79"+7.8%
Sidewall height6.02"6.50"+0.47"+7.8%
Circumference91.25"94.22"+2.97"+3.3%
Revolutions per mile694.3672.4−21.9−3.2%

Speedometer difference

If your vehicle came with 255/60R17 and you fit 275/60R17, 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 mph51.6 mph+1.6 mph
60 mph62.0 mph+2.0 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.4 mph+2.4 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 255/60R17 or 275/60R17?
275/60R17 is taller by 0.94 inches (29.99" vs 29.05"). 275/60R17 is wider by 0.79 inches.
Can I replace 255/60R17 with 275/60R17?
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 275/60R17 change my speedometer?
When your speedometer reads 60 mph with 275/60R17 fitted (calibrated for 255/60R17), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 275/60R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.47 inches of ground clearance at the axle.

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