Tire Size Box

235/80R14 vs 255/80R14

255/80R14 compared with 235/80R14

+4.4% diameter, +0.8" width

255/80R14 is 30.06" 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 255/80R14 (dashed outline), drawn to scale

With 255/80R14 tires, when your speedometer says 60 mph you are really going

62.6 mph

255/80R14 is +1.26 inches (+4.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/80R14255/80R14Difference%
Overall diameter28.80"30.06"+1.26"+4.4%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height7.40"8.03"+0.63"+8.5%
Circumference90.49"94.45"+3.96"+4.4%
Revolutions per mile700.2670.9−29.3−4.2%

Speedometer difference

If your vehicle came with 235/80R14 and you fit 255/80R14, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.9 mph+0.9 mph
30 mph31.3 mph+1.3 mph
40 mph41.7 mph+1.7 mph
50 mph52.2 mph+2.2 mph
60 mph62.6 mph+2.6 mph
65 mph67.8 mph+2.8 mph
70 mph73.1 mph+3.1 mph
75 mph78.3 mph+3.3 mph
80 mph83.5 mph+3.5 mph

Each size on its own

Questions

Which is bigger, 235/80R14 or 255/80R14?
255/80R14 is taller by 1.26 inches (30.06" vs 28.80"). 255/80R14 is wider by 0.79 inches.
Can I replace 235/80R14 with 255/80R14?
It is not recommended without checking carefully. The diameter difference is +4.4%, 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 255/80R14 change my speedometer?
When your speedometer reads 60 mph with 255/80R14 fitted (calibrated for 235/80R14), your real speed is 62.6 mph. Your odometer will under-count miles by about 4.4%.
Will 255/80R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.63 inches of ground clearance at the axle.

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