Tires: vibration, Tire Vibration

Question
I own a 2004 Toyota Tacoma 4X4 with 75,000 miles on it.  Last month I took my truck to a local front end alignment and tire shop.  I had the front end aligned and 2 new Mastercraft Tires put on the front.  On my way home I noticed a vibration in the front end at around 65 mph.  I returned the truck the following day and they rebalanced the tires.  No front end vibration since then.  
This month I returned the truck to the same tire shop and had matching tires put on the rear. (had to buy 2 tires per payday).
Once the rear tires were put on I traveled home and again noticed a vibration at around 60 to 65 mph, but this time I felt it in my seat and rear end.  I returned the truck again and had the tires rebalanced but this did not solve the problem.  The shop rebalanced the tires 3 times with no luck.  I was still experiencing a vibration that was not there before.  The tire shop owner drove my truck and said it had to be a faulty set of tires.  So………….he ordered 4 new Dayton tires and put them on my truck.   As he was balancing these new tires he told me that one of my rims was slightly bent but he did not understand why because there are no scratches, dents or trauma to the rim.  After installing the tires he then said he found 3 rims on my truck which here slightly bent and he had to add “a lot of weight to the tires”.  I traveled home and still noticed the vibration at 60 – 65 mph.  The vibration that was NOT there prior to taking this truck to the tire shop.  
My truck is basically not used as a truck………I purchased it new and it is in mint condition. It has never been involved in an accident or hit a bump or curb.  There is no dent, scratch or trauma visible on my wheels.  I have never hauled anything heavier than a small piece of furniture and I have never pulled anything.  It does not even have a hitch.  Is it possible that the machine used to balance my tires is not calibrated.  They have put loads of weight on each wheel.   What else could cause this sudden vibration?  
Thanks


Answer
Kelly,

Obviously it has something to do with the tire change.

Wheel end vibrations are usually felt between 50 and 70 mph - and that matches!

Wheel end vibrations in the front are felt in the steering wheel - that matcghes, too! - and wheel end vibrations in the rear are felt in the seat or floorboard - Bingo!

First I would see if you can find a Hunter GSP9700 Road Force Machine.  That will be able to sort out if it is the tire or the rim.  (BTW, you can dent a rim and not have marks, because the tire is protecting the rim.)

Here's how to find one:

http://www.gsp9700.com/pub/search/findgsp9700.cfm