Tire Size Box

255/55R16 vs 255/65R16

255/65R16 compared with 255/55R16

+7.4% diameter, 0.0" width

255/65R16 is 29.05" tall vs 27.04". More than the 3% rule of thumb, so check carefully before switching.

27.0"16" rim5.5"10.0" wide
255/55R16 (solid) compared with 255/65R16 (dashed outline), drawn to scale

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

64.5 mph

255/65R16 is +2.01 inches (+7.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

255/55R16255/65R16Difference%
Overall diameter27.04"29.05"+2.01"+7.4%
Section width10.04"10.04"0.00"0.0%
Sidewall height5.52"6.53"+1.00"+18.2%
Circumference84.96"91.27"+6.31"+7.4%
Revolutions per mile745.8694.2−51.5−6.9%

Speedometer difference

If your vehicle came with 255/55R16 and you fit 255/65R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.5 mph+1.5 mph
30 mph32.2 mph+2.2 mph
40 mph43.0 mph+3.0 mph
50 mph53.7 mph+3.7 mph
60 mph64.5 mph+4.5 mph
65 mph69.8 mph+4.8 mph
70 mph75.2 mph+5.2 mph
75 mph80.6 mph+5.6 mph
80 mph85.9 mph+5.9 mph

Each size on its own

Questions

Which is bigger, 255/55R16 or 255/65R16?
255/65R16 is taller by 2.01 inches (29.05" vs 27.04"). 255/55R16 is the same width.
Can I replace 255/55R16 with 255/65R16?
It is not recommended without checking carefully. The diameter difference is +7.4%, 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 255/65R16 change my speedometer?
When your speedometer reads 60 mph with 255/65R16 fitted (calibrated for 255/55R16), your real speed is 64.5 mph. Your odometer will under-count miles by about 7.4%.
Will 255/65R16 lift my vehicle?
Ride height changes by half the diameter difference: +1.00 inches of ground clearance at the axle.

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