Tire Size Box

285/65R15 vs 285/70R15

285/70R15 compared with 285/65R15

+3.8% diameter, 0.0" width

285/70R15 is 30.71" 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 285/70R15 (dashed outline), drawn to scale

With 285/70R15 tires, when your speedometer says 60 mph you are really going

62.3 mph

285/70R15 is +1.12 inches (+3.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/65R15285/70R15Difference%
Overall diameter29.59"30.71"+1.12"+3.8%
Section width11.22"11.22"0.00"0.0%
Sidewall height7.29"7.85"+0.56"+7.7%
Circumference92.95"96.47"+3.53"+3.8%
Revolutions per mile681.7656.8−24.9−3.7%

Speedometer difference

If your vehicle came with 285/65R15 and you fit 285/70R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.8 mph+2.8 mph
80 mph83.0 mph+3.0 mph

Each size on its own

Questions

Which is bigger, 285/65R15 or 285/70R15?
285/70R15 is taller by 1.12 inches (30.71" vs 29.59"). 285/65R15 is the same width.
Can I replace 285/65R15 with 285/70R15?
It is not recommended without checking carefully. The diameter difference is +3.8%, 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 285/70R15 change my speedometer?
When your speedometer reads 60 mph with 285/70R15 fitted (calibrated for 285/65R15), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.8%.
Will 285/70R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.56 inches of ground clearance at the axle.

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