Decoded notation
255 mm / 40% / R / 18 in
Popular Tire Sizes
255/40R18 Tire Size — Dimensions & Revs
Decode 255/40R18 and calculate nominal width, sidewall, overall diameter, circumference and revolutions.
Calculated dimensions are nominal values based on tire-size notation; actual measured dimensions vary.
Width255 mm
Sidewall height102.0 mm
Rim diameter18 in
Overall diameter661.2 mm
Overall diameter26.03 in
Circumference2077.2 mm
Revolutions per mile774.8
Revolutions per km481.4