[shorod]

Does anything seem loose with the weight of the car off of the tire, but with the tire and wheel still mounted (using the leverage of the wheel and tire to wiggle)? You want to be sure the ball joints and tie rod ends are still tight.

You may have a wheel balance issue (maybe a wheel weight recently fell off), a bent wheel, bad wheel bearing, bad CV joint, and possibly an alignment issue. However, if you have any loose suspension components, they are likely to cause the car to be out of alignment.

If your issue were only a wheel balance issue, I would expect the vibration to be very noticeable in the steering wheel.

From your description, I would suggest that your car is not safe for highway speeds, inspect the suspension and steering closely. If you don't find anything, have a professional inspect it closely before driving it any more than absolutely necessary. If nothing else, your tires are not safe for highway speeds. Keep in mind that it's not just your safety that you are potentially risking.

-Rod