Tire Size Box

265/85R15 vs 285/85R15

285/85R15 compared with 265/85R15

+4.1% diameter, +0.8" width

285/85R15 is 34.07" tall vs 32.74". More than the 3% rule of thumb, so check carefully before switching.

32.7"15" rim8.9"10.4" wide
265/85R15 (solid) compared with 285/85R15 (dashed outline), drawn to scale

With 285/85R15 tires, when your speedometer says 60 mph you are really going

62.5 mph

285/85R15 is +1.34 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/85R15285/85R15Difference%
Overall diameter32.74"34.07"+1.34"+4.1%
Section width10.43"11.22"+0.79"+7.5%
Sidewall height8.87"9.54"+0.67"+7.5%
Circumference102.84"107.05"+4.21"+4.1%
Revolutions per mile616.1591.9−24.2−3.9%

Speedometer difference

If your vehicle came with 265/85R15 and you fit 285/85R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.6 mph+1.6 mph
50 mph52.0 mph+2.0 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 mph
70 mph72.9 mph+2.9 mph
75 mph78.1 mph+3.1 mph
80 mph83.3 mph+3.3 mph

Each size on its own

Questions

Which is bigger, 265/85R15 or 285/85R15?
285/85R15 is taller by 1.34 inches (34.07" vs 32.74"). 285/85R15 is wider by 0.79 inches.
Can I replace 265/85R15 with 285/85R15?
It is not recommended without checking carefully. The diameter difference is +4.1%, 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 285/85R15 change my speedometer?
When your speedometer reads 60 mph with 285/85R15 fitted (calibrated for 265/85R15), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.1%.
Will 285/85R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.67 inches of ground clearance at the axle.

Other comparisons