I am driving now and my car shakes very badley. It shakes with speed, and if i am doing lets are 80 it is alot more smoother riding than when i am doing 40. It feels like i have a bent wheel, which i dont.

i was thinking about maybe a wheel bearing. Throwout some options that it could be

 

Balance/alignment/tire wear.

 

Check your lugnuts

-matt

 

my wheels are in prefect balance and alignment. i have had it done acouple times. my wheel are always tight i have checked the most common problems

 

balance your wheels...or one of your tires are underinflated. One of the problems is from it being lowerd though...your cambers are probably off. Making your tires have bald spots in certain places. good luck

 

How's the wear on those tires?

 

http://forums.maxima.org/showthread.php?t=532706

 

This might be a stupid response, but check the tire thread, maybe you put the rims on backwords. I accidently did that one time on my old max, and i had crap loads of vibration, till i rotated the tireds and make sure the thread was facing the right way.