After a 600 mile road trip this weekend that included some rough highways and construction areas that were rough on the suspension, I'm now having a strange vibration through the steering wheel. It starts around 15-20mph with the steering wheel rocking back and forth about 1/2". As speed increases the rocking turns to more of a standard vibration to the point at about 70+mph its hard to distinguish it from road feel, but it is definitely still there. The rocking is very weird and to have it get better instead of worse with rpm increases also seems strange.

I'm hoping it's just wheel imbalance as maybe I lost some wheel weights, but want to know if there is anything else I should look at before taking the wheels in. So far I have not noticed any other symptoms and it seems to steer and handle fine.

Depending on how long you were on rough surfaces, I have seen everything from suspension components becoming loose, to wheel weights falling off (generally not a low speed problem). I would get it on a lift and make sure everything is tight.

I did 600+ miles on washboard at 40-80MPH and it loosened up just about every part of my car

Thanks, I guess that will be the first step tonight to get it jacked up and start looking for any loose bolts or damage, was just hoping for pointers on anything specific that I need to look at.

Turns out the issue was simple, the inside of the front tires were gone, but couldn't see how bad until I got underneath it. A new set of fronts and the shake is gone.

I was going to mention the possibility of a broken belt in the tire, but you replaced the tires. Might get the alignment checked unless you enjoy buying new skins on a frequent basis...