Diameter - Measured radially at the flattest portion of the bead seat.
Wheel Width - Measured transversely at the most vertical part of the bead seat.
Overall Rim Width - Measured transversely at the outside of the rim.
Rear Spacing or Backspacing - Measured transversely from the inside rim face to the mounting surface.
Offset - Distance from the center of the rim plane to the mounting surface plane. To calculate offset, use
Offset = Backspacing - Overall Rim Width/2
928 Tips Home Greg's Home