Vibration in steering wheel

Lately my steering seems to be doing alot of vibrating as i am driving down the road.
So I was wondering if one of you experts could shed some light as to what the problem might be. Yes I know, it could be a number of things but lets go through the list.
02 X (4x4) 57K miles, original tires, struts, steering equipment.
Yes I know, the tires are old and will be replaced soon.
So, which of the following could be causing the problem?
1- tires old
2- tires out of balance
3- struts old and have lost their dampening
4- alignment
5- ball joints, etc.

Any and all useful insight will be greately appreciated (notice I said "useful")!
Thanks

I'd look at the tire presure first, a difference in a few PSI can cause vibration in the steering.
I'm guessing you probably checked that, but you didn't say so or list it, and it's a cheap and easy check and fix (and easy to overlook).

Yah, tire pressires are all set (34 psi).
I am sure all probable causes are having some influence but I just want to confirm and start from the least expensive to the most expensive (tires).

Anyone else with ideas?

Could also be the brake rotors warped. Im not positive, but i think if it was warped rotors you would feel it all the time. You would also feel it in the brake pedal.

I have also read several posts on the forum regarding to centerlink and other front steering components, but i have no idea how to check them.
Jay

just noticed that the steering box is leaking - could that be the cause of all the vibration??
I have the extended warranty so the appointment as been made for Monday.
Called the parts department to see if they had any in stock. Steering box assembly is $1900 (parts only) and 2 days to get one.
Thank God for extended warranty! (not that I would be paying that amount if I had no warranty!)

As far as the rotor thing - if I am not applying the brakes I don't think there would be any vibration.

I had the same problem after I had gotten my tires rotated. They said that the problem was that the wheels were not balanced. That seemed to solve the problem of the steering wheel vibrating.