Tire Size Box

235/65R19 vs 255/65R19

255/65R19 compared with 235/65R19

+3.3% diameter, +0.8" width

255/65R19 is 32.05" tall vs 31.03". More than the 3% rule of thumb, so check carefully before switching.

31.0"19" rim6.0"9.3" wide
235/65R19 (solid) compared with 255/65R19 (dashed outline), drawn to scale

With 255/65R19 tires, when your speedometer says 60 mph you are really going

62.0 mph

255/65R19 is +1.02 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/65R19255/65R19Difference%
Overall diameter31.03"32.05"+1.02"+3.3%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height6.01"6.53"+0.51"+8.5%
Circumference97.48"100.69"+3.22"+3.3%
Revolutions per mile650.0629.2−20.8−3.2%

Speedometer difference

If your vehicle came with 235/65R19 and you fit 255/65R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph62.0 mph+2.0 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.5 mph+2.5 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 235/65R19 or 255/65R19?
255/65R19 is taller by 1.02 inches (32.05" vs 31.03"). 255/65R19 is wider by 0.79 inches.
Can I replace 235/65R19 with 255/65R19?
It is not recommended without checking carefully. The diameter difference is +3.3%, 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 255/65R19 change my speedometer?
When your speedometer reads 60 mph with 255/65R19 fitted (calibrated for 235/65R19), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 255/65R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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