Well the truck sounds like it is now properly aligned, but now your truck could be pulling because of the tire wear. Try swapping the front two tires and see if it pulls the other direction. If so, then you know it's the tires. Buy new ones. If not, then the truck is not aligned properly.
I think that should help you figure things out. I'm sure others will chime in if they have other/better advice/experience etc.
I think that should help you figure things out. I'm sure others will chime in if they have other/better advice/experience etc.