255/70R17 vs 255/80R17

255/80R17 is 2.0" taller than 255/70R17 (6.5%)

Diameter difference+6.47%diameter 31.06" → 33.06"
255/70R17255/80R17
255/70R17255/80R17Difference
Overall diameter31.06"33.06"+2.01"
Section width10.04"10.04"±0.00"
Sidewall height7.03"8.03"+1.00"
Circumference97.6"103.9"+6.3"
Revolutions per mile649610−39
Wheel diameter17"17"±0"

Speedometer

ShowsActualDiff
30 mph31.9 mph+1.9
45 mph47.9 mph+2.9
60 mph63.9 mph+3.9
70 mph74.5 mph+4.5
80 mph85.2 mph+5.2

Gear ratio to match

CurrentEquivalent
3.423.64
3.553.78
3.733.97
4.104.37

255/80R17 is 2.01" taller than 255/70R17, a +6.47% change in diameter. That is more than the 3% many tire shops use as a limit, so plan on recalibrating the speedometer and checking ABS and stability control.

Ground clearance changes by 1.00" (half the diameter change), and the tire needs 1.00" more room above it.

Both tires are the same width, 10.04".

Both fit a 17" wheel; the sidewall is 1.00" taller on 255/80R17.

Details: 255/70R17 in inches · 255/80R17 in inches · change sizes in the calculator

FAQ

What is the difference between 255/70R17 and 255/80R17?

255/80R17 is 2.01" taller (+6.47%) and 0.00" wider than 255/70R17.

Will 255/80R17 change my speedometer?

Yes, by +6.47%. When the speedometer shows 60 mph you would be going 63.9 mph.

Can I replace 255/70R17 with 255/80R17?

It is a +6.5% diameter change, larger than the common 3% guideline, so check clearance and plan to recalibrate.