Archive has higher Page Rank

I realized that my archive has higher page ranks then regular forums. For example Biyografiler [Arþiv] - Ayyas has a PR 4 but Biyografiler - Ayyas has a PR 3 it is same as nearly all my archive.

In my vBSeo Archive settings i have Archive Options:Rewrite + 301 Redirect vB's Archive.

Now i am thinking why i shall redirect the threads ? Which setting do you recommend me to go. Suprisingly my archive has a higher Page Rank and i shall want my archive to get indexed i think. On the other hand keeping this settings also seems to be logical because i'll have a PR4 page linked to my threads and which will eventually help those threads to get better rankings.