Tire Size Box

235/70R14 vs 235/80R14

235/80R14 compared with 235/70R14

+6.9% diameter, 0.0" width

235/80R14 is 28.80" tall vs 26.95". More than the 3% rule of thumb, so check carefully before switching.

27.0"14" rim6.5"9.3" wide
235/70R14 (solid) compared with 235/80R14 (dashed outline), drawn to scale

With 235/80R14 tires, when your speedometer says 60 mph you are really going

64.1 mph

235/80R14 is +1.85 inches (+6.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/70R14235/80R14Difference%
Overall diameter26.95"28.80"+1.85"+6.9%
Section width9.25"9.25"0.00"0.0%
Sidewall height6.48"7.40"+0.93"+14.3%
Circumference84.67"90.49"+5.81"+6.9%
Revolutions per mile748.3700.2−48.1−6.4%

Speedometer difference

If your vehicle came with 235/70R14 and you fit 235/80R14, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.4 mph+1.4 mph
30 mph32.1 mph+2.1 mph
40 mph42.7 mph+2.7 mph
50 mph53.4 mph+3.4 mph
60 mph64.1 mph+4.1 mph
65 mph69.5 mph+4.5 mph
70 mph74.8 mph+4.8 mph
75 mph80.1 mph+5.1 mph
80 mph85.5 mph+5.5 mph

Each size on its own

Questions

Which is bigger, 235/70R14 or 235/80R14?
235/80R14 is taller by 1.85 inches (28.80" vs 26.95"). 235/70R14 is the same width.
Can I replace 235/70R14 with 235/80R14?
It is not recommended without checking carefully. The diameter difference is +6.9%, 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 235/80R14 change my speedometer?
When your speedometer reads 60 mph with 235/80R14 fitted (calibrated for 235/70R14), your real speed is 64.1 mph. Your odometer will under-count miles by about 6.9%.
Will 235/80R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

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