Tire Size Box

265/75R18 vs 285/75R18

285/75R18 compared with 265/75R18

+3.5% diameter, +0.8" width

285/75R18 is 34.83" tall vs 33.65". More than the 3% rule of thumb, so check carefully before switching.

33.6"18" rim7.8"10.4" wide
265/75R18 (solid) compared with 285/75R18 (dashed outline), drawn to scale

With 285/75R18 tires, when your speedometer says 60 mph you are really going

62.1 mph

285/75R18 is +1.18 inches (+3.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/75R18285/75R18Difference%
Overall diameter33.65"34.83"+1.18"+3.5%
Section width10.43"11.22"+0.79"+7.5%
Sidewall height7.82"8.42"+0.59"+7.5%
Circumference105.71"109.42"+3.71"+3.5%
Revolutions per mile599.4579.0−20.3−3.4%

Speedometer difference

If your vehicle came with 265/75R18 and you fit 285/75R18, 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 mph77.6 mph+2.6 mph
80 mph82.8 mph+2.8 mph

Each size on its own

Questions

Which is bigger, 265/75R18 or 285/75R18?
285/75R18 is taller by 1.18 inches (34.83" vs 33.65"). 285/75R18 is wider by 0.79 inches.
Can I replace 265/75R18 with 285/75R18?
It is not recommended without checking carefully. The diameter difference is +3.5%, 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 285/75R18 change my speedometer?
When your speedometer reads 60 mph with 285/75R18 fitted (calibrated for 265/75R18), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.5%.
Will 285/75R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.59 inches of ground clearance at the axle.

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