ok well honestly i think that your wheel allignment is off, it happens to all of us, it might also be your ABS goin' nutz if you have ABS that is, if its neither of those then it could be that your wheels may not be balanced properly. otherwise i really have no idea what it could be.... well there is one other thing, it could be one or both of the rear struts are damaged but it takes some serious pounding to break, bend, or "pop" a strut... but those are my best guesses. The first things i would do if i were you is i would check my tire pressures, pump em up to like 35-37 psi, go over a bump and see if it still does it. if it does then goto your local goodyear, pepboys, or a gas station(last option is gas station b/c they dont usually warranty their work) and ask if they would be nice enough to just check if your car is alligned properly. and if it is out of allignment have them allign it, then go out and go over a bump and see if it does it again. If it was alligned fine to begin with then what you should do is then have them see if the wheels are balanced, if they aren't have them balanced. then go out and hit that bump again to see if you still have the same problem. If all of that fails then i'd have to say that your suspension might be damaged. oh i almost forgot, after filling your tired up to 35-37 psi drive around for a day or so, and then go back and check the tire pressures, you might have a leak as well... thats the best i can do... hope one of them helps

 

Sounds like alignment to me. Goodyears suck major ***...but my car did not even do that with them and I had maybe 40% tread last year when I had them. When the pavement is dry out does your car pull hard to left or right at all? Sounds like the back is fighting itself to me.

 

lol i wasnt saying get goodyear tires...... i said goto a goodyear shop, they do allignments.... lol i hate goodyear tires, i'd rather get myself a michelin(sp?)