You can try more. I had bad luck too.
My problem was moisture in the tire causing the smaller Dynabeads to clump.

 

So I am giving it one more try tomorrow. I am adding 3oz to each tire making it 11oz. If it doesn't work then, it's time to suck them out!!!!!

 

i have 12oz in my tires and its not enough....37" trail graps

 

So is there a point where not enough is too much and it just isnt going to work????

 

Added three more ounces to each yesterday all now at 11oz. First trip looks like all ok until 75 then it loses it's crap!!!!

 

Just did my BFGs 285/75/17 with 6oz in each. The guys at Farm and Fleet looked at me like I was nuts. Until they spun them up and took it for a ride. They'll be doing more big tires now.

 

my main issue is around 40-50 id be happy with not going over 75 since it hardly ever happens

 

Well it looks like I am removing the beads tomorrow and attempting to balance again. Life is great to 55 and then it is just too iffy for me. I head to camp often and it's 1.5 hours on the highway. I just can't stand how sporadic it is after 55. One minute it is smooth at a speed over 55 then it's not. It also tends to jump around a bit after a big bump. That doesn't work so well here in Maine with bumps and holes everywhere.