Tire Size Box

235/65R14 vs 255/65R14

255/65R14 compared with 235/65R14

+3.9% diameter, +0.8" width

255/65R14 is 27.05" tall vs 26.03". More than the 3% rule of thumb, so check carefully before switching.

26.0"14" rim6.0"9.3" wide
235/65R14 (solid) compared with 255/65R14 (dashed outline), drawn to scale

With 255/65R14 tires, when your speedometer says 60 mph you are really going

62.4 mph

255/65R14 is +1.02 inches (+3.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/65R14255/65R14Difference%
Overall diameter26.03"27.05"+1.02"+3.9%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height6.01"6.53"+0.51"+8.5%
Circumference81.77"84.98"+3.22"+3.9%
Revolutions per mile774.9745.6−29.3−3.8%

Speedometer difference

If your vehicle came with 235/65R14 and you fit 255/65R14, 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 mph62.4 mph+2.4 mph
65 mph67.6 mph+2.6 mph
70 mph72.8 mph+2.8 mph
75 mph77.9 mph+2.9 mph
80 mph83.1 mph+3.1 mph

Each size on its own

Questions

Which is bigger, 235/65R14 or 255/65R14?
255/65R14 is taller by 1.02 inches (27.05" vs 26.03"). 255/65R14 is wider by 0.79 inches.
Can I replace 235/65R14 with 255/65R14?
It is not recommended without checking carefully. The diameter difference is +3.9%, 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 255/65R14 change my speedometer?
When your speedometer reads 60 mph with 255/65R14 fitted (calibrated for 235/65R14), your real speed is 62.4 mph. Your odometer will under-count miles by about 3.9%.
Will 255/65R14 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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