You have a few options here: Get your wheels balanced-cheapest, have a mechanic check your steering components for wear-possibly more expensive or third, drive faster than 45mph everywhere-probably most expensive(fuel and possible speeding tickets)and the least safe. :)
Warped rotors
allignment
Tire out of balance or bent wheel.
bent drive axle or axles
usually steering shakes over 60 mph is due to front tires needing to be balanced unless you have something more serious going on.
My steering wheel shakes what could this mean? _____ try getting your car re-aligned.
Yes, you can still drive it. You may have a tire out of balance or a wheel bearing getting bad. However, have a mechanic check it out soon.
Tire out of balance, bent wheel, belt broken in tire, loose or worn steering components, loose wheel bearing, loose lug nuts, or suspension parts worn.
you need to balance the tires or thelug nuts are loose
Wheel balance
there is a chance that your rotors are warped and need replacing"Possible"
Probably i would go for wheel balance and maybe check your wheel bearings rotors will not make it shake because of speed