As a contractor working with pneumatic air hoses of all materials and sizes, I can tell you guys that the softer, more pliable hoses are the ones used for such things as fountain soda machines. Pneumatic hoses are thicker and more durable, hence also stiffer.
I have my hoses ready to dye but I'd rather try and find the softer hoses, which I am trying to do right now. I've been slowly working on my v. 2 Jango gauntlets for some time. I know there's a thread around here for dying hoses. I'll find it.
Edit: Found it:
http://www.thedentedhelmet.com/showpost.php?p=60512&postcount=160
I've heard that denim blue RIT dye works well. That's what I bought. I'm just waiting for my Dark-Side darts to arrive and I should be able to finish my gauntlets.