1. A wheel construction, comprising: hollow, moldable hub means made of acrylonitrilebutadienestyrene and having an axially extending cylindrical sleeve portion with a central opening therethrough, cylindrical peripheral wall means concentric with said sleeve portion and spaced radially outwardly therefrom, a pair of axially spaced and generally radially extending side wall means for connecting the corresponding axial ends of said sleeve portion and said peripheral wall means, and means defining annular grooves at the opposite ends of said peripheral wall means, each of said grooves opening both radially and axially; and moldable tread means made of polyurethane and defining an endless channel having a pair of flanges and a web portion, said flanges being received into said annular grooves and said web portion engaging said peripheral wall means, said tread means being concentric with said peripheral wall means, said hub means and said tread means having a face-to-face mutually adhering bond therebetween, said bond formed by applying said polyurethane to said hub in a molten state.

7. A wheel construction, comprising: hub means having a pair of identical halves made of an acrylonitrile-butadiene-styrene materIal, each half consisting of a cylindrical sleeve portion with a central opening therethrough, a radially outwardly extending wall integral with said sleeve adjacent one end thereof, a cylindrical peripheral wall concentric with said sleeve portion and integral at one end with the radially outer edge of said radial wall and a plurality of radial webs secured to said radial wall and secured to and extending between said sleeve portion and said peripheral wall, the edges of said sleeve portion, said peripheral wall and said radial webs remote from said radial wall terminating in a plane perpendicular to the axis of said central opening, said hub halves being disposed in reflecting positions on opposite sides of said plane; and tread means made of a moldable polyurethane material and defining an endless channel having a pair of flanges and a web, said flanges snugly engaging the remote axial ends of said peripheral walls of said hub halves, said tread means and said hub means having a face-to-face mutually adhering bond therebetween, said bond formed by applying said polyurethane to said hub in a molten state, whereby to hold said hub halves together and said web snugly engaging said peripheral walls.

8. A wheel construction, comprising: a pair of identical hub halves engaged along a common radial plane and including means for securing said hub halves together, said hub halves being made of an acrylonitrile-butadiene-styrene material; moldable tread means made of polyurethane material molded around the periphery of said hub halves, said tread means and said hub means having a face-to-face mutually adhering bond therebetween, said bond formed by applying said polyurethane to said hub in a molten state, the axially facing surfaces of said hub halves and said tread means being smooth and unbroken.

9. In a method for making a wheel, the steps comprising: placing a pair of separate and coaxial hub halves made of acrylonitrile-butadiene-styrene material side-by-side into a mold having an annular cavity of uniform thickness around the periphery of said hub halves, the radially inner wall of said cavity being defined at least in part by the portion of said hub halves adjacent the periphery thereof; and injecting a moldable polyurethane material in a molten state into said mold cavity around the periphery of said hub halves, said moldable polyurethane forming a face-to-face mutually adhering bond with said hub halves to form a tread for said wheel construction concentric with said hub halves.