(1) The diameter of the wheel; also the inside
    diameter of the tire.  Use an 8" wheel with an
    8" tire.
(2)The width of the wheel.
(3)Most wheels are centered, with no offset. An
    offset is indicated as, for example, 3+5,
    meaning3" off-center inside and 5" offset to
    the outside.
(4)Number of bolt holes in the wheel.
(5)Spacing of bolt holes (usually in millimeters),
    measured from center of hole across center of
    wheel to center of opposite bolt hole.