This is a spoked wheel blank intended to be printed in metal and to be machined by the buyer to final dimensions. The printing process for metal is not sufficiently precise to directly produce finished precision wheels. The part model has added material to allow for expected shrinkage so that the blank can be finished to a 1.59" diameter outer rim, a 1.438" diameter tread, and 0.375" thickness.
Ed Hume's book, A Climax Class A Live Steam Locomotive, has detailed dimensions and provides a detailed workflow for painting and machining the wheel blank on a lathe. There is more information on the book and locomotive design at http://Model-Shop.net.