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255/70R17 vs 255/65R18 tire size

255/65R18 vs 255/70R17, diameter

Same diameter

Speedometer
60.0 mph
At a true 60 mph
Diameter
31.05 in
Was 31.06 in
Revs per mile
650
Was 649
3% guideline
Within

Car built for 255/70R17, now on 255/65R18.

255/70R17 and 255/65R18

255/70R17 vs 255/65R18 tire size
Measure255/70R17255/65R18Difference
Width, mm2552550
Sidewall, % of width7065-5
Rim, in1718+1
Section height, in7.036.53-0.50
Diameter, in31.0631.050 (-0.0%)
Circumference, in97.697.6-0.0
Revs per mile649650+0 (+0.0%)

Fitting 255/65R18 instead of 255/70R17

Within the usual 3% diameter guideline.

  • Needs 18 in wheels.
  • Shorter sidewall: 0.5 in less.

Cars with 255/70R17

Cars with 255/65R18

What this cannot tell you

Diameter within 3% is a common shop guideline, not a maker spec.

Load index, offset and clearance are not in this data.

How values are checked