Tire Size Box

235/80R14 vs 235/85R14

235/85R14 compared with 235/80R14

+3.2% diameter, 0.0" width

235/85R14 is 29.73" tall vs 28.80". More than the 3% rule of thumb, so check carefully before switching.

28.8"14" rim7.4"9.3" wide
235/80R14 (solid) compared with 235/85R14 (dashed outline), drawn to scale

With 235/85R14 tires, when your speedometer says 60 mph you are really going

61.9 mph

235/85R14 is +0.93 inches (+3.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/80R14235/85R14Difference%
Overall diameter28.80"29.73"+0.93"+3.2%
Section width9.25"9.25"0.00"0.0%
Sidewall height7.40"7.86"+0.46"+6.3%
Circumference90.49"93.39"+2.91"+3.2%
Revolutions per mile700.2678.4−21.8−3.1%

Speedometer difference

If your vehicle came with 235/80R14 and you fit 235/85R14, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.1 mph+2.1 mph
70 mph72.2 mph+2.2 mph
75 mph77.4 mph+2.4 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 235/80R14 or 235/85R14?
235/85R14 is taller by 0.93 inches (29.73" vs 28.80"). 235/80R14 is the same width.
Can I replace 235/80R14 with 235/85R14?
It is not recommended without checking carefully. The diameter difference is +3.2%, 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 235/85R14 change my speedometer?
When your speedometer reads 60 mph with 235/85R14 fitted (calibrated for 235/80R14), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.2%.
Will 235/85R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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