Tire Size Box

265/65R18 vs 285/65R18

285/65R18 compared with 265/65R18

+3.2% diameter, +0.8" width

285/65R18 is 32.59" tall vs 31.56". More than the 3% rule of thumb, so check carefully before switching.

31.6"18" rim6.8"10.4" wide
265/65R18 (solid) compared with 285/65R18 (dashed outline), drawn to scale

With 285/65R18 tires, when your speedometer says 60 mph you are really going

61.9 mph

285/65R18 is +1.02 inches (+3.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/65R18285/65R18Difference%
Overall diameter31.56"32.59"+1.02"+3.2%
Section width10.43"11.22"+0.79"+7.5%
Sidewall height6.78"7.29"+0.51"+7.5%
Circumference99.16"102.37"+3.22"+3.2%
Revolutions per mile639.0618.9−20.1−3.1%

Speedometer difference

If your vehicle came with 265/65R18 and you fit 285/65R18, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.4 mph+2.4 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 265/65R18 or 285/65R18?
285/65R18 is taller by 1.02 inches (32.59" vs 31.56"). 285/65R18 is wider by 0.79 inches.
Can I replace 265/65R18 with 285/65R18?
It is not recommended without checking carefully. The diameter difference is +3.2%, 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 285/65R18 change my speedometer?
When your speedometer reads 60 mph with 285/65R18 fitted (calibrated for 265/65R18), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.2%.
Will 285/65R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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