any speed related vibration is almost always related to tires and wheels. If it come and goes at different speeds , ie shakes at 45 and goes away at 60 , is a balance issue, Lower speeds is usually and out of round tire. You cant just jack up the front end to check suspension. you have to jack it up from under the lower control arm, especially a strut car. You have to unload the lower control arm to check tie rod ends and ball joints. A brake pulsation is definitly the rotors but a high speed vibration is most likely a wheel balance problem