Tire Size Box

265/65R20 vs 285/65R20

285/65R20 compared with 265/65R20

+3.0% diameter, +0.8" width

285/65R20 is 34.59" tall vs 33.56". More than the 3% rule of thumb, so check carefully before switching.

33.6"20" rim6.8"10.4" wide
265/65R20 (solid) compared with 285/65R20 (dashed outline), drawn to scale

With 285/65R20 tires, when your speedometer says 60 mph you are really going

61.8 mph

285/65R20 is +1.02 inches (+3.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/65R20285/65R20Difference%
Overall diameter33.56"34.59"+1.02"+3.0%
Section width10.43"11.22"+0.79"+7.5%
Sidewall height6.78"7.29"+0.51"+7.5%
Circumference105.44"108.66"+3.22"+3.0%
Revolutions per mile600.9583.1−17.8−3.0%

Speedometer difference

If your vehicle came with 265/65R20 and you fit 285/65R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.2 mph+1.2 mph
50 mph51.5 mph+1.5 mph
60 mph61.8 mph+1.8 mph
65 mph67.0 mph+2.0 mph
70 mph72.1 mph+2.1 mph
75 mph77.3 mph+2.3 mph
80 mph82.4 mph+2.4 mph

Each size on its own

Questions

Which is bigger, 265/65R20 or 285/65R20?
285/65R20 is taller by 1.02 inches (34.59" vs 33.56"). 285/65R20 is wider by 0.79 inches.
Can I replace 265/65R20 with 285/65R20?
It is not recommended without checking carefully. The diameter difference is +3.0%, 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 285/65R20 change my speedometer?
When your speedometer reads 60 mph with 285/65R20 fitted (calibrated for 265/65R20), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.0%.
Will 285/65R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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