Tire Size Box

235/75R14 vs 235/85R14

235/85R14 compared with 235/75R14

+6.6% diameter, 0.0" width

235/85R14 is 29.73" tall vs 27.88". More than the 3% rule of thumb, so check carefully before switching.

27.9"14" rim6.9"9.3" wide
235/75R14 (solid) compared with 235/85R14 (dashed outline), drawn to scale

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

64.0 mph

235/85R14 is +1.85 inches (+6.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/75R14235/85R14Difference%
Overall diameter27.88"29.73"+1.85"+6.6%
Section width9.25"9.25"0.00"0.0%
Sidewall height6.94"7.86"+0.93"+13.3%
Circumference87.58"93.39"+5.81"+6.6%
Revolutions per mile723.4678.4−45.0−6.2%

Speedometer difference

If your vehicle came with 235/75R14 and you fit 235/85R14, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.3 mph+1.3 mph
30 mph32.0 mph+2.0 mph
40 mph42.7 mph+2.7 mph
50 mph53.3 mph+3.3 mph
60 mph64.0 mph+4.0 mph
65 mph69.3 mph+4.3 mph
70 mph74.6 mph+4.6 mph
75 mph80.0 mph+5.0 mph
80 mph85.3 mph+5.3 mph

Each size on its own

Questions

Which is bigger, 235/75R14 or 235/85R14?
235/85R14 is taller by 1.85 inches (29.73" vs 27.88"). 235/75R14 is the same width.
Can I replace 235/75R14 with 235/85R14?
It is not recommended without checking carefully. The diameter difference is +6.6%, 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 235/85R14 change my speedometer?
When your speedometer reads 60 mph with 235/85R14 fitted (calibrated for 235/75R14), your real speed is 64.0 mph. Your odometer will under-count miles by about 6.6%.
Will 235/85R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

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