I just finished my second set of ice tires, I can grab ya some pics of them tonight if ya want.
I have had good luck with a 2-3 pattern, 3 studs in one row, 2 studs in the next, 3 in the next etc.....
I am gonna try 70 per tire this year. I will be out this weekend to try them out. I will let ya know how it goes.