thx guys, I dont really rush my install, I am careful about it especially since I keep getting these kind of tears. I do run my fingers on both the rim and tire as well as a good ol wipe wth a cloth or something just to see if I "shake" something lose. Im hoping the babypowder or I just bought a faulty tube. So far it seems like I have to replace 2-3 tubes (same brand, same method) until I get lucky and it does not tear.

-andychrist the valve tear was my first. The other tears are never in the same place, at least so far wth 6 different tubes.
-NS1 yes its always the rear lol.

FYI the tubes im using are bell brand. My kenda tube (original) also tore after a few hundred miles, same thing it didnt tear while on the road but rather when its just sitting in my living room.