Tire Size Box

285/55R15 vs 285/65R15

285/65R15 compared with 285/55R15

+8.2% diameter, 0.0" width

285/65R15 is 29.59" tall vs 27.34". More than the 3% rule of thumb, so check carefully before switching.

27.3"15" rim6.2"11.2" wide
285/55R15 (solid) compared with 285/65R15 (dashed outline), drawn to scale

With 285/65R15 tires, when your speedometer says 60 mph you are really going

64.9 mph

285/65R15 is +2.24 inches (+8.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/55R15285/65R15Difference%
Overall diameter27.34"29.59"+2.24"+8.2%
Section width11.22"11.22"0.00"0.0%
Sidewall height6.17"7.29"+1.12"+18.2%
Circumference85.90"92.95"+7.05"+8.2%
Revolutions per mile737.6681.7−55.9−7.6%

Speedometer difference

If your vehicle came with 285/55R15 and you fit 285/65R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.5 mph+2.5 mph
40 mph43.3 mph+3.3 mph
50 mph54.1 mph+4.1 mph
60 mph64.9 mph+4.9 mph
65 mph70.3 mph+5.3 mph
70 mph75.7 mph+5.7 mph
75 mph81.2 mph+6.2 mph
80 mph86.6 mph+6.6 mph

Each size on its own

Questions

Which is bigger, 285/55R15 or 285/65R15?
285/65R15 is taller by 2.24 inches (29.59" vs 27.34"). 285/55R15 is the same width.
Can I replace 285/55R15 with 285/65R15?
It is not recommended without checking carefully. The diameter difference is +8.2%, 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 285/65R15 change my speedometer?
When your speedometer reads 60 mph with 285/65R15 fitted (calibrated for 285/55R15), your real speed is 64.9 mph. Your odometer will under-count miles by about 8.2%.
Will 285/65R15 lift my vehicle?
Ride height changes by half the diameter difference: +1.12 inches of ground clearance at the axle.

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