Tire Size Box

235/70R14 vs 255/70R14

255/70R14 compared with 235/70R14

+4.1% diameter, +0.8" width

255/70R14 is 28.06" 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 255/70R14 (dashed outline), drawn to scale

With 255/70R14 tires, when your speedometer says 60 mph you are really going

62.5 mph

255/70R14 is +1.10 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/70R14255/70R14Difference%
Overall diameter26.95"28.06"+1.10"+4.1%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height6.48"7.03"+0.55"+8.5%
Circumference84.67"88.14"+3.46"+4.1%
Revolutions per mile748.3718.9−29.4−3.9%

Speedometer difference

If your vehicle came with 235/70R14 and you fit 255/70R14, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.6 mph+1.6 mph
50 mph52.0 mph+2.0 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 mph
70 mph72.9 mph+2.9 mph
75 mph78.1 mph+3.1 mph
80 mph83.3 mph+3.3 mph

Each size on its own

Questions

Which is bigger, 235/70R14 or 255/70R14?
255/70R14 is taller by 1.10 inches (28.06" vs 26.95"). 255/70R14 is wider by 0.79 inches.
Can I replace 235/70R14 with 255/70R14?
It is not recommended without checking carefully. The diameter difference is +4.1%, 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 255/70R14 change my speedometer?
When your speedometer reads 60 mph with 255/70R14 fitted (calibrated for 235/70R14), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.1%.
Will 255/70R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.55 inches of ground clearance at the axle.

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