Decoded notation
255 mm / 40% / R / 21 in
Popular Tire Sizes
255/40R21 Tire Size — Dimensions & Revs
Decode 255/40R21 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 diameter21 in
Overall diameter737.4 mm
Overall diameter29.03 in
Circumference2316.6 mm
Revolutions per mile694.7
Revolutions per km431.7