Tire Size Box

275/55R15 vs 275/65R15

275/65R15 compared with 275/55R15

+8.0% diameter, 0.0" width

275/65R15 is 29.07" tall vs 26.91". More than the 3% rule of thumb, so check carefully before switching.

26.9"15" rim6.0"10.8" wide
275/55R15 (solid) compared with 275/65R15 (dashed outline), drawn to scale

With 275/65R15 tires, when your speedometer says 60 mph you are really going

64.8 mph

275/65R15 is +2.17 inches (+8.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/55R15275/65R15Difference%
Overall diameter26.91"29.07"+2.17"+8.0%
Section width10.83"10.83"0.00"0.0%
Sidewall height5.95"7.04"+1.08"+18.2%
Circumference84.54"91.34"+6.80"+8.0%
Revolutions per mile749.5693.7−55.8−7.4%

Speedometer difference

If your vehicle came with 275/55R15 and you fit 275/65R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.4 mph+2.4 mph
40 mph43.2 mph+3.2 mph
50 mph54.0 mph+4.0 mph
60 mph64.8 mph+4.8 mph
65 mph70.2 mph+5.2 mph
70 mph75.6 mph+5.6 mph
75 mph81.0 mph+6.0 mph
80 mph86.4 mph+6.4 mph

Each size on its own

Questions

Which is bigger, 275/55R15 or 275/65R15?
275/65R15 is taller by 2.17 inches (29.07" vs 26.91"). 275/55R15 is the same width.
Can I replace 275/55R15 with 275/65R15?
It is not recommended without checking carefully. The diameter difference is +8.0%, 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 275/65R15 change my speedometer?
When your speedometer reads 60 mph with 275/65R15 fitted (calibrated for 275/55R15), your real speed is 64.8 mph. Your odometer will under-count miles by about 8.0%.
Will 275/65R15 lift my vehicle?
Ride height changes by half the diameter difference: +1.08 inches of ground clearance at the axle.

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