im guessing it has something to do with velocity and road conditions. yet again, if i'd imagine that a steering wheel shouldn't shake.... that can't be good.
It could be a shifted belt in one of the tires.
This can be a warped rotor or tire out of balance. If it only happens when braking it is a warped rotor.
== == Bad Tire or Tires.
COULD BE FRONT TIE ROD END
High speed vibration is often an indication of a wheel that is out of balance or a bent rim. It can also be a bent driveshaft or bad U-joint. Vibration when you brake at high speed is almost always a warped rotor on the disk brakes.
Tire out of balance, bent wheel, drive shaft bent, loose or worn steering parts.
At low speed: Damaged or failed tire, bent wheel, damaged brake, damaged axle. Dangerous failure of a wheel bearing. At high speed generally a wheel balanace problem. While braking a bent or warped brake component.
have front suspension checked
You rotors are warped and will need replaced/resurfaced.
Your brake rotors are warped.
You probably need to get your tires balanced. Or replaced. If the bias goes (steel belt breaks or shifts), the car will waddle at low speeds, and the steering wheel will shake at high speeds.
I would suspect wheel balance is the problem but the steering and suspension system such as tie rod ends, pitman arm, idler arm, steering box, ball joints and control arm bushings if applicable should be checked also.