What part in LEGO digital designer can be used for a tank track?
The caterpillar track and belt are both fixed length pieces.

I would recommend the more versatile #57518 'Technic, Link Tread Wide with Two Pin Holes'. The part can be used to make a track as long as long as you like.



The tread is compatible with:


#57519 - Technic Tread Sprocket Wheel Large
#57520 -  Technic Tread Sprocket Wheel Small