Tire Size Box

285/65R15 vs 285/75R15

285/75R15 compared with 285/65R15

+7.6% diameter, 0.0" width

285/75R15 is 31.83" tall vs 29.59". More than the 3% rule of thumb, so check carefully before switching.

29.6"15" rim7.3"11.2" wide
285/65R15 (solid) compared with 285/75R15 (dashed outline), drawn to scale

With 285/75R15 tires, when your speedometer says 60 mph you are really going

64.6 mph

285/75R15 is +2.24 inches (+7.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/65R15285/75R15Difference%
Overall diameter29.59"31.83"+2.24"+7.6%
Section width11.22"11.22"0.00"0.0%
Sidewall height7.29"8.42"+1.12"+15.4%
Circumference92.95"100.00"+7.05"+7.6%
Revolutions per mile681.7633.6−48.1−7.1%

Speedometer difference

If your vehicle came with 285/65R15 and you fit 285/75R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.5 mph+1.5 mph
30 mph32.3 mph+2.3 mph
40 mph43.0 mph+3.0 mph
50 mph53.8 mph+3.8 mph
60 mph64.6 mph+4.6 mph
65 mph69.9 mph+4.9 mph
70 mph75.3 mph+5.3 mph
75 mph80.7 mph+5.7 mph
80 mph86.1 mph+6.1 mph

Each size on its own

Questions

Which is bigger, 285/65R15 or 285/75R15?
285/75R15 is taller by 2.24 inches (31.83" vs 29.59"). 285/65R15 is the same width.
Can I replace 285/65R15 with 285/75R15?
It is not recommended without checking carefully. The diameter difference is +7.6%, 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 285/75R15 change my speedometer?
When your speedometer reads 60 mph with 285/75R15 fitted (calibrated for 285/65R15), your real speed is 64.6 mph. Your odometer will under-count miles by about 7.6%.
Will 285/75R15 lift my vehicle?
Ride height changes by half the diameter difference: +1.12 inches of ground clearance at the axle.

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