Raychem DR-25

I am planning on building my harness what should be the appropriate size I should order for the sheathing ??

6mm (¼”):

10mm (⅜”):

I find it helpful to stock 1/8", 3/16", 1/4" and 3/8" for most harnesses. Sometimes I will need short sections of 1/2" and 3/4" -- it all depends on the diameter of your wire bundle. You will find you need more of the smaller, and less of the larger for most Engine / Data harnesses.

perfect thanks for the advice! it will be my first time building my own harness from scratch! figuring out the proper dr-25 to order.

Depending how "professional' you want it, and your budget(!), you may need to check out the "break-out" options, which are like "Y" shaped heat-shrink sleeves that seal where cables leave the main loom.