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215/65R17 vs 255/50R18 tire size

255/50R18 vs 215/65R17, diameter

+0.1% taller

Speedometer
59.9 mph
At a true 60 mph
Diameter
28.04 in
Was 28.00 in
Revs per mile
719
Was 720
3% guideline
Within

Car built for 215/65R17, now on 255/50R18.

215/65R17 and 255/50R18

215/65R17 vs 255/50R18 tire size
Measure215/65R17255/50R18Difference
Width, mm215255+40
Sidewall, % of width6550-15
Rim, in1718+1
Section height, in5.505.02-0.48
Diameter, in28.0028.04+0.04 (+0.1%)
Circumference, in88.088.1+0.1
Revs per mile720719-1 (-0.1%)

Fitting 255/50R18 instead of 215/65R17

Within the usual 3% diameter guideline.

  • Needs 18 in wheels.
  • 40 mm wider. Check rubbing at full lock.

Cars with 215/65R17

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