Tire Size Box

255/65R17 vs 275/65R17

275/65R17 compared with 255/65R17

+3.4% diameter, +0.8" width

275/65R17 is 31.07" tall vs 30.05". More than the 3% rule of thumb, so check carefully before switching.

30.1"17" rim6.5"10.0" wide
255/65R17 (solid) compared with 275/65R17 (dashed outline), drawn to scale

With 275/65R17 tires, when your speedometer says 60 mph you are really going

62.0 mph

275/65R17 is +1.02 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

255/65R17275/65R17Difference%
Overall diameter30.05"31.07"+1.02"+3.4%
Section width10.04"10.83"+0.79"+7.8%
Sidewall height6.53"7.04"+0.51"+7.8%
Circumference94.41"97.62"+3.22"+3.4%
Revolutions per mile671.1649.0−22.1−3.3%

Speedometer difference

If your vehicle came with 255/65R17 and you fit 275/65R17, 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 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.0 mph+2.0 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 255/65R17 or 275/65R17?
275/65R17 is taller by 1.02 inches (31.07" vs 30.05"). 275/65R17 is wider by 0.79 inches.
Can I replace 255/65R17 with 275/65R17?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 275/65R17 change my speedometer?
When your speedometer reads 60 mph with 275/65R17 fitted (calibrated for 255/65R17), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.4%.
Will 275/65R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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