Tire Size Box

205/75R15 vs 205/85R15

205/85R15 compared with 205/75R15

+6.0% diameter, 0.0" width

205/85R15 is 28.72" tall vs 27.11". More than the 3% rule of thumb, so check carefully before switching.

27.1"15" rim6.1"8.1" wide
205/75R15 (solid) compared with 205/85R15 (dashed outline), drawn to scale

With 205/85R15 tires, when your speedometer says 60 mph you are really going

63.6 mph

205/85R15 is +1.61 inches (+6.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

205/75R15205/85R15Difference%
Overall diameter27.11"28.72"+1.61"+6.0%
Section width8.07"8.07"0.00"0.0%
Sidewall height6.05"6.86"+0.81"+13.3%
Circumference85.16"90.23"+5.07"+6.0%
Revolutions per mile744.0702.2−41.8−5.6%

Speedometer difference

If your vehicle came with 205/75R15 and you fit 205/85R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.2 mph+1.2 mph
30 mph31.8 mph+1.8 mph
40 mph42.4 mph+2.4 mph
50 mph53.0 mph+3.0 mph
60 mph63.6 mph+3.6 mph
65 mph68.9 mph+3.9 mph
70 mph74.2 mph+4.2 mph
75 mph79.5 mph+4.5 mph
80 mph84.8 mph+4.8 mph

Each size on its own

Questions

Which is bigger, 205/75R15 or 205/85R15?
205/85R15 is taller by 1.61 inches (28.72" vs 27.11"). 205/75R15 is the same width.
Can I replace 205/75R15 with 205/85R15?
It is not recommended without checking carefully. The diameter difference is +6.0%, 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 205/85R15 change my speedometer?
When your speedometer reads 60 mph with 205/85R15 fitted (calibrated for 205/75R15), your real speed is 63.6 mph. Your odometer will under-count miles by about 6.0%.
Will 205/85R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.81 inches of ground clearance at the axle.

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