Yeah, when I had my new wheels installed I had them re-torqued after about 70ish miles and re-torqued again after another 50 or so.

 

Generally speaking, under torque will not cause studs to break. It will cause wheels to fall off, though.
First question - where are they breaking? Flush with the hub or out a bit? As asked earlier, do you have spacers? Are the lugnuts correct for these wheels?

 

Ding ding ding!!!!! ^^^. Right answer!^^^^

I think you need hub centric rings to allow the rim to sit completely centered on the hub and not the studs... Your wheels will all loosen no matter how tight you make them because the wheel is not being centered properly by the lugs alone... I've had all 4 wheels loosen up on me at once because I didn't use hub rings on my bronco... Get the plastic hub rings. They are cheap and won't fuse to the hub like the metal ones will. I'm positive this is your issue...
The studs integrity are more then likely compromised at this point and you may want to replace all of them....

The best way to tell if you need hub centric rings quickly is to pull your center cap off and see if the hub bore on the rim is resting on the hub of the truck...