When I get tired of the feeling, seeing as I don’t destroy trucks like I used to. It’s a feeling thing for me. I hate tinkering with my trucks so I just change ‘em when I’m over them, I don‘t mind breaking in new trucks, in fact, I enjoy it.
Could be a month (Krux), could be years (Indy). I’ve got 2 and a half years on my Ventures right now and don’t feel the need to change them, I love the feeling and they’re perfect for me.