Tire Size Box

235/80R16 vs 255/80R16

255/80R16 compared with 235/80R16

+4.1% diameter, +0.8" width

255/80R16 is 32.06" tall vs 30.80". More than the 3% rule of thumb, so check carefully before switching.

30.8"16" rim7.4"9.3" wide
235/80R16 (solid) compared with 255/80R16 (dashed outline), drawn to scale

With 255/80R16 tires, when your speedometer says 60 mph you are really going

62.5 mph

255/80R16 is +1.26 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/80R16255/80R16Difference%
Overall diameter30.80"32.06"+1.26"+4.1%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height7.40"8.03"+0.63"+8.5%
Circumference96.77"100.73"+3.96"+4.1%
Revolutions per mile654.7629.0−25.7−3.9%

Speedometer difference

If your vehicle came with 235/80R16 and you fit 255/80R16, 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, 235/80R16 or 255/80R16?
255/80R16 is taller by 1.26 inches (32.06" vs 30.80"). 255/80R16 is wider by 0.79 inches.
Can I replace 235/80R16 with 255/80R16?
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 255/80R16 change my speedometer?
When your speedometer reads 60 mph with 255/80R16 fitted (calibrated for 235/80R16), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.1%.
Will 255/80R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.63 inches of ground clearance at the axle.

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