Tire Size Box

155/75R14 vs 155/85R14

155/85R14 compared with 155/75R14

+5.3% diameter, 0.0" width

155/85R14 is 24.37" tall vs 23.15". More than the 3% rule of thumb, so check carefully before switching.

23.2"14" rim4.6"6.1" wide
155/75R14 (solid) compared with 155/85R14 (dashed outline), drawn to scale

With 155/85R14 tires, when your speedometer says 60 mph you are really going

63.2 mph

155/85R14 is +1.22 inches (+5.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

155/75R14155/85R14Difference%
Overall diameter23.15"24.37"+1.22"+5.3%
Section width6.10"6.10"0.00"0.0%
Sidewall height4.58"5.19"+0.61"+13.3%
Circumference72.74"76.57"+3.83"+5.3%
Revolutions per mile871.1827.4−43.6−5.0%

Speedometer difference

If your vehicle came with 155/75R14 and you fit 155/85R14, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.1 mph+1.1 mph
30 mph31.6 mph+1.6 mph
40 mph42.1 mph+2.1 mph
50 mph52.6 mph+2.6 mph
60 mph63.2 mph+3.2 mph
65 mph68.4 mph+3.4 mph
70 mph73.7 mph+3.7 mph
75 mph79.0 mph+4.0 mph
80 mph84.2 mph+4.2 mph

Each size on its own

Questions

Which is bigger, 155/75R14 or 155/85R14?
155/85R14 is taller by 1.22 inches (24.37" vs 23.15"). 155/75R14 is the same width.
Can I replace 155/75R14 with 155/85R14?
It is not recommended without checking carefully. The diameter difference is +5.3%, 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 155/85R14 change my speedometer?
When your speedometer reads 60 mph with 155/85R14 fitted (calibrated for 155/75R14), your real speed is 63.2 mph. Your odometer will under-count miles by about 5.3%.
Will 155/85R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.61 inches of ground clearance at the axle.

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