Major tire vibration

[rcjmaxx]

I bought a used OFNA Titan monster truck roller,after converting it to brushless I found that at about 30 mph it swirves sharply out of controll.Some suspension adjusting made a small difference.With the truck suspended and all 4 tire off the ground,I ran the rpm's up a little and you could see all 4 tires VIOLENTLY shaking and vibrating.I'm assuming the wheels/tires are out of balance...but at 30 mph? Am I assuming correctly? Is there a solution to this problem? Thanks in advance.