Tire Size Box

155/80R14 vs 155/85R14

155/85R14 compared with 155/80R14

+2.6% diameter, 0.0" width

155/85R14 is 24.37" tall vs 23.76". Within the 3% rule, so usually interchangeable.

23.8"14" rim4.9"6.1" wide
155/80R14 (solid) compared with 155/85R14 (dashed outline), drawn to scale

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

61.5 mph

155/85R14 is +0.61 inches (+2.6%) in overall diameter. That is within the 3% most shops and makers allow.

155/80R14155/85R14Difference%
Overall diameter23.76"24.37"+0.61"+2.6%
Section width6.10"6.10"0.00"0.0%
Sidewall height4.88"5.19"+0.31"+6.3%
Circumference74.66"76.57"+1.92"+2.6%
Revolutions per mile848.7827.4−21.2−2.5%

Speedometer difference

If your vehicle came with 155/80R14 and you fit 155/85R14, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.5 mph+0.5 mph
30 mph30.8 mph+0.8 mph
40 mph41.0 mph+1.0 mph
50 mph51.3 mph+1.3 mph
60 mph61.5 mph+1.5 mph
65 mph66.7 mph+1.7 mph
70 mph71.8 mph+1.8 mph
75 mph76.9 mph+1.9 mph
80 mph82.1 mph+2.1 mph

Each size on its own

Questions

Which is bigger, 155/80R14 or 155/85R14?
155/85R14 is taller by 0.61 inches (24.37" vs 23.76"). 155/80R14 is the same width.
Can I replace 155/80R14 with 155/85R14?
Usually, yes. The diameter difference is +2.6%, inside the 3% rule of thumb most tire shops use. Check that the wider or taller tire clears your suspension and fenders, and that its load index meets your placard.
How much will 155/85R14 change my speedometer?
When your speedometer reads 60 mph with 155/85R14 fitted (calibrated for 155/80R14), your real speed is 61.5 mph. Your odometer will under-count miles by about 2.6%.
Will 155/85R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.31 inches of ground clearance at the axle.

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