Greetings!
If you are experiencing a speed specific vibration, then it is almost certainly wheel or tire related. The one exception would be if you bent the hub that the wheel is mounted to.
The hub can be checked for damage with a dial indicator; anything over .002 runout can result in a vibration.
It is more likely a damaged wheel or a tire that is mounted with the high side of the tire and the high point of the rim aligned resulting in an out of round wheel assembly.
There is a machine on the market that is designed specifically to detect and correct the cause of vibrations such as this; I will give you a link to the manufacturer'sweb site which has a shop locator to find one in your area.
This machine (Hunter GSP9700) is unique in that it measures vibrations being generated under actual rotational conditions using a load roller with a transducer attached. It also measures the wheel and the entire assembly for roundness and parallelism. This machine works extremely well at resolving this kind of vibration issue; it is supposed to be a required piece of eqiipment at GM and Chrysler dealerships in the near future.
Measurement and balancing with this equipment typically costs the same as conventional balancing, which does not have the capability of detecting most of the causes of vibrations other than weight imbalance. It is almost impossible to visually see .005 inch of rim distortion with the naked eye, although this amount WILL induce a vibration concern.
Here is the link to the shop locator:
http://www.hunter.com/pub/product/balancer/index.htm
I hope thsi is helpful; if so, an accept would be most aprpeciated! thanks!
