Tire Size Box

265/80R15 vs 265/85R15

265/85R15 compared with 265/80R15

+3.3% diameter, 0.0" width

265/85R15 is 32.74" tall vs 31.69". More than the 3% rule of thumb, so check carefully before switching.

31.7"15" rim8.3"10.4" wide
265/80R15 (solid) compared with 265/85R15 (dashed outline), drawn to scale

With 265/85R15 tires, when your speedometer says 60 mph you are really going

62.0 mph

265/85R15 is +1.04 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/80R15265/85R15Difference%
Overall diameter31.69"32.74"+1.04"+3.3%
Section width10.43"10.43"0.00"0.0%
Sidewall height8.35"8.87"+0.52"+6.2%
Circumference99.57"102.84"+3.28"+3.3%
Revolutions per mile636.4616.1−20.3−3.2%

Speedometer difference

If your vehicle came with 265/80R15 and you fit 265/85R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph62.0 mph+2.0 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.5 mph+2.5 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 265/80R15 or 265/85R15?
265/85R15 is taller by 1.04 inches (32.74" vs 31.69"). 265/80R15 is the same width.
Can I replace 265/80R15 with 265/85R15?
It is not recommended without checking carefully. The diameter difference is +3.3%, 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 265/85R15 change my speedometer?
When your speedometer reads 60 mph with 265/85R15 fitted (calibrated for 265/80R15), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 265/85R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.52 inches of ground clearance at the axle.

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