Tire Size Box

235/70R16 vs 255/70R16

255/70R16 compared with 235/70R16

+3.8% diameter, +0.8" width

255/70R16 is 30.06" tall vs 28.95". More than the 3% rule of thumb, so check carefully before switching.

29.0"16" rim6.5"9.3" wide
235/70R16 (solid) compared with 255/70R16 (dashed outline), drawn to scale

With 255/70R16 tires, when your speedometer says 60 mph you are really going

62.3 mph

255/70R16 is +1.10 inches (+3.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/70R16255/70R16Difference%
Overall diameter28.95"30.06"+1.10"+3.8%
Section width9.25"10.04"+0.79"+8.5%
Sidewall height6.48"7.03"+0.55"+8.5%
Circumference90.96"94.42"+3.46"+3.8%
Revolutions per mile696.6671.0−25.5−3.7%

Speedometer difference

If your vehicle came with 235/70R16 and you fit 255/70R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.9 mph+2.9 mph
80 mph83.0 mph+3.0 mph

Each size on its own

Questions

Which is bigger, 235/70R16 or 255/70R16?
255/70R16 is taller by 1.10 inches (30.06" vs 28.95"). 255/70R16 is wider by 0.79 inches.
Can I replace 235/70R16 with 255/70R16?
It is not recommended without checking carefully. The diameter difference is +3.8%, 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 255/70R16 change my speedometer?
When your speedometer reads 60 mph with 255/70R16 fitted (calibrated for 235/70R16), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.8%.
Will 255/70R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.55 inches of ground clearance at the axle.

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