Worn tires front or rear?

I am putting my summer tires back on and one pair (that was in the back) has more thread than the ones that were in front.

Should IlI put the tires that are most worn in front or rear?

 

Worn tires in front, less tread in the rear will turn your truck into a tree magnet in slippery conditions.

 

For optimal wet handling, the tires with less tread depth should be installed in the front.

 

New tires in the rear. The shop I worked at in college would make you sign a waiver if you wanted the new tires on the front, and there were other shops that would flat out deny service if you wanted new tires on the front instead of rear.