Tire Size Box

185/70R16 vs 185/80R16

185/80R16 compared with 185/70R16

+5.6% diameter, 0.0" width

185/80R16 is 27.65" tall vs 26.20". More than the 3% rule of thumb, so check carefully before switching.

26.2"16" rim5.1"7.3" wide
185/70R16 (solid) compared with 185/80R16 (dashed outline), drawn to scale

With 185/80R16 tires, when your speedometer says 60 mph you are really going

63.3 mph

185/80R16 is +1.46 inches (+5.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/70R16185/80R16Difference%
Overall diameter26.20"27.65"+1.46"+5.6%
Section width7.28"7.28"0.00"0.0%
Sidewall height5.10"5.83"+0.73"+14.3%
Circumference82.30"86.88"+4.58"+5.6%
Revolutions per mile769.9729.3−40.6−5.3%

Speedometer difference

If your vehicle came with 185/70R16 and you fit 185/80R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.1 mph+1.1 mph
30 mph31.7 mph+1.7 mph
40 mph42.2 mph+2.2 mph
50 mph52.8 mph+2.8 mph
60 mph63.3 mph+3.3 mph
65 mph68.6 mph+3.6 mph
70 mph73.9 mph+3.9 mph
75 mph79.2 mph+4.2 mph
80 mph84.4 mph+4.4 mph

Each size on its own

Questions

Which is bigger, 185/70R16 or 185/80R16?
185/80R16 is taller by 1.46 inches (27.65" vs 26.20"). 185/70R16 is the same width.
Can I replace 185/70R16 with 185/80R16?
It is not recommended without checking carefully. The diameter difference is +5.6%, 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 185/80R16 change my speedometer?
When your speedometer reads 60 mph with 185/80R16 fitted (calibrated for 185/70R16), your real speed is 63.3 mph. Your odometer will under-count miles by about 5.6%.
Will 185/80R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.73 inches of ground clearance at the axle.

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