Tires: Streering Wheel Vibrates, cv joints, suspension components

Question
I am not sure this problem is about teh tires, but may be you can help.  I bought a used Honda Odyssys 2000.  The steering wheel vibrates when I drive 75-80 mph and also when I step on the brake at fast speed.  I took it back to the dealer 2-3 times for alignment.  They can only get it better but not gone.  What causes it & how can it be fixed.

Answer
Pat,

There are quite a few things that might be causing this,

Tires, warped brakes rotors, worn suspension components, bent wheel, CV joints.

Needless to say each has its own fix.  I would start with the brakes - it's the most important item on the list.