where can i get 0.15 or bigger jazz strings?

I make mine from singles. I was never able to find a premade set.

 

0.15 inch?? That's not a jazz string. That's a bass string!

(0.15 inch is thicker than 1/8th inch = 0.125 inch.)

 

Thomastik-Infeld makes sets up to .014. After that I'd guess you need to make sets up yourself.

Check out:

http://www.juststrings.com/electricguitar.html

Edit: Just saw on that site that LaBella makes a .015 set of flatwounds.