Tire Size Box

285/70R17 vs 285/75R17

285/75R17 compared with 285/70R17

+3.4% diameter, 0.0" width

285/75R17 is 33.83" tall vs 32.71". More than the 3% rule of thumb, so check carefully before switching.

32.7"17" rim7.9"11.2" wide
285/70R17 (solid) compared with 285/75R17 (dashed outline), drawn to scale

With 285/75R17 tires, when your speedometer says 60 mph you are really going

62.1 mph

285/75R17 is +1.12 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/70R17285/75R17Difference%
Overall diameter32.71"33.83"+1.12"+3.4%
Section width11.22"11.22"0.00"0.0%
Sidewall height7.85"8.42"+0.56"+7.1%
Circumference102.76"106.28"+3.53"+3.4%
Revolutions per mile616.6596.1−20.5−3.3%

Speedometer difference

If your vehicle came with 285/70R17 and you fit 285/75R17, 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 mph62.1 mph+2.1 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, 285/70R17 or 285/75R17?
285/75R17 is taller by 1.12 inches (33.83" vs 32.71"). 285/70R17 is the same width.
Can I replace 285/70R17 with 285/75R17?
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 285/75R17 change my speedometer?
When your speedometer reads 60 mph with 285/75R17 fitted (calibrated for 285/70R17), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.4%.
Will 285/75R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.56 inches of ground clearance at the axle.

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