Decoded notation
305 mm / 40% / R / 21 in
Popular Tire Sizes
305/40R21 Tire Size — Dimensions & Revs
Decode 305/40R21 and calculate nominal width, sidewall, overall diameter, circumference and revolutions.
Calculated dimensions are nominal values based on tire-size notation; actual measured dimensions vary.
Width305 mm
Sidewall height122.0 mm
Rim diameter21 in
Overall diameter777.4 mm
Overall diameter30.61 in
Circumference2442.3 mm
Revolutions per mile659.0
Revolutions per km409.5