Is it possible to add a grouser to the 3 inch wide track for better traction on snow?
The tracks is pretty much production, so any modifications would need to be done on your end. You can see a CAD file of the track to see if you can make the modifications:
lynxmotion.com/s-5-ses-3d-models.aspx#tracks
If you can custom-design one, we do have a 3D printing service:
3dprinting.robotshop.com/
Excellent! Is the track made of two different materials?
The core of each tread is made of injection molded plastic and there is a rubber tread added as a second process (also injection molded and cannot be separated from the plastic).