2005 Nissan Altima-Steering wheel shakes @ 55-70 mph

Unbalanced tire

pull out spark plugs and see if they all look the same,could be dirty fuel injectors or a blocked fuel filter

If the steering wheel starts to shake between 55-65 MPH then you need to balance the wheels. If it shakes when you press the brakes, your brake rotors are warped and need to be cut or replaced. If the steering wheel shakes at low speeds then it's possible one of your rims is bent or one of your tires is out of round. Leaving a car parked for a long time in snowy and icy roads will damage your tires, causing them to warp. Depending on which situation is causing your steering wheel to shake, have it looked at.

Hub or tire is out of balance....

Have tires Dynamically balanced

More than likely, you have warped brake rotors. If thats not it, a tire has a belt broken and needs to be replaced.

could have bent rim,,even thow,,balance was done,,depends on how mush weight was used to balance?? rotate tires from frt to rear,,see if problem still exits,,ck bearing play,,hoped it helped

If you got high miles on this vehicle I'd call it at front upper strut bushing and the struts. If the dealer did a front and rear Alignment ONE WOULD HOPE THAT HE WOULD HAVE FOUND THIS. I'm gonna give him the benefit of the doubt and say that the tires are probably overinflated. Check tire pressure when vehicle is cold or you drove under a mile.Most Tech overinflat tires during balancing.

I have this same car with exactly the same problem. Begins shaking at 40mph and stops shaking as soon as you let off the gas, but then begins again as soon as you press on the gas and smooths out as you get over 50. And the shaking is not felt through the steering wheel. Solution: Replace the transmission mounts. There are two of them, one on each side mounted on the frame right next to the shock strut. There is also a front and rear engine mount, but I replaced the two as described and shaking is gone.

It may be that one of your front wheel rims is slightly buckled. You can try swapping each with your spare wheel then test drive and see if this eliminates the problem.

bent wheel, defective tire cord, out of balace tire.