Red Oak Butterscotch Traditional Left Return Stair Tread 72 in

These treads are 1" thick +- 1/64". The overall length of the tread includes the return so think of the length as the "tip to tip" front measurement. Each return is 1 1/4" wide. This particular tread is 72" wide overall which means there is 70 3/4" straight stock. If you were measuring a 42" left return tread, the inside width would be 40 3/4" wide.

Here is a link to an image with example dimensions:

http://www.stair-treads.com/images/stair-tread-dimensions.jpg