Tires shaking and bouncing violent

I recently installed 40" groundhog tires on my 79' Ford f-100 custom and  when going down the road at speeds 25mph and over, every now and then, the steering will start shaking and pulling rapidly left and right  and the front end will bounce so violently that I must bring the truck almost to a stop or around 10mph for fear that parts will begin to break or shake off of it!  The truck had three Rancho steering stabilizers and I was told by a few mechanics that it was overkill and was heavily taxing my powersteering which has an upgraded heavy duty kit from an F-350.  In responce to that I had two of them removed.  What are the causes of this and what can I do to fix it

  hey guy.....check your steering gear box ........it might be flexing in the frame......the fix is too box the frame and remount your steering gear box.........good luck

a long time ago i had a couple of ford trucks, a 73, a 74 and a 79. The 73 and 79 were 4 x 4s, the 74 was a 2 x 4. the 74 had the same trouble and it turned out to be king pins, a bad idler arm and out of balance tires. the 73 and 79 occasionally had the problem. start replacing the idler arm or tie rod ends first then check your ball joints, if you haven't already done so. also, make sure your tires are as true as possible and balanced.     good luck  

your tires are probably bad are the radial or bias?  
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You know I love you all (in a manly non sexual way) Spawn_X

Way to dig up a six year old thread... lol  
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