Short story:
My 1989 LWB shakes when it is driven at speeds above 45 mph and it gets worse until it hits 65 mph. At 65 mph the shaking gets tolerable. I suspect the tires are to blame, they have 60,000 miles on them and enough thread for a short trip. I do plan to buy new tires if necessary.

Long story:
In less than two weeks I have to travel 1,000 miles from mid Missouri to home, (El Paso, TX). After I get home I will be leaving the country for at least one year.

The point:
I want to be able to make it home safely, is there any possibility its not the tires? What else could cause the shaking? Any suggestions to what else look for?

Thanks in advance.