Tire Size Box

235/65R16 vs 255/65R16

255/65R16 compared with 235/65R16

+3.7% diameter, +0.8" width

255/65R16 is 29.05" tall vs 28.03". More than the 3% rule of thumb, so check carefully before switching.

28.0"16" rim6.0"9.3" wide
235/65R16 (solid) compared with 255/65R16 (dashed outline), drawn to scale

With 255/65R16 tires, when your speedometer says 60 mph you are really going

62.2 mph

255/65R16 is +1.02 inches (+3.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/65R16255/65R16Difference%
Overall diameter28.03"29.05"+1.02"+3.7%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height6.01"6.53"+0.51"+8.5%
Circumference88.05"91.27"+3.22"+3.7%
Revolutions per mile719.6694.2−25.4−3.5%

Speedometer difference

If your vehicle came with 235/65R16 and you fit 255/65R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.8 mph+1.8 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.6 mph+2.6 mph
75 mph77.7 mph+2.7 mph
80 mph82.9 mph+2.9 mph

Each size on its own

Questions

Which is bigger, 235/65R16 or 255/65R16?
255/65R16 is taller by 1.02 inches (29.05" vs 28.03"). 255/65R16 is wider by 0.79 inches.
Can I replace 235/65R16 with 255/65R16?
It is not recommended without checking carefully. The diameter difference is +3.7%, 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 255/65R16 change my speedometer?
When your speedometer reads 60 mph with 255/65R16 fitted (calibrated for 235/65R16), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.7%.
Will 255/65R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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