Tire Size Box

285/65R17 vs 285/70R17

285/70R17 compared with 285/65R17

+3.6% diameter, 0.0" width

285/70R17 is 32.71" tall vs 31.59". More than the 3% rule of thumb, so check carefully before switching.

31.6"17" rim7.3"11.2" wide
285/65R17 (solid) compared with 285/70R17 (dashed outline), drawn to scale

With 285/70R17 tires, when your speedometer says 60 mph you are really going

62.1 mph

285/70R17 is +1.12 inches (+3.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/65R17285/70R17Difference%
Overall diameter31.59"32.71"+1.12"+3.6%
Section width11.22"11.22"0.00"0.0%
Sidewall height7.29"7.85"+0.56"+7.7%
Circumference99.23"102.76"+3.53"+3.6%
Revolutions per mile638.5616.6−21.9−3.4%

Speedometer difference

If your vehicle came with 285/65R17 and you fit 285/70R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.4 mph+1.4 mph
50 mph51.8 mph+1.8 mph
60 mph62.1 mph+2.1 mph
65 mph67.3 mph+2.3 mph
70 mph72.5 mph+2.5 mph
75 mph77.7 mph+2.7 mph
80 mph82.8 mph+2.8 mph

Each size on its own

Questions

Which is bigger, 285/65R17 or 285/70R17?
285/70R17 is taller by 1.12 inches (32.71" vs 31.59"). 285/65R17 is the same width.
Can I replace 285/65R17 with 285/70R17?
It is not recommended without checking carefully. The diameter difference is +3.6%, 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 285/70R17 change my speedometer?
When your speedometer reads 60 mph with 285/70R17 fitted (calibrated for 285/65R17), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.6%.
Will 285/70R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.56 inches of ground clearance at the axle.

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