So I just replaced my rear tires with falken 512's, previously had yoko s drives. all around. First thing i noticed is that my car likes to oversteer now and while driving in a straight line at higher speeds is very sketchy. Feels like its gonna go off the road and the rear end swerves..? Is this because these tires suck? rear trailing arm bushing? alignment?

 

My first guess would be due to alignment. When ever you do anything such as removing a wheel or mounting new tires you mess with the cars alignment. Before I flipped and rotated tires, my car pulls towards the right but now it's less severe cus tires flipped and the side with camber wear was causing the swerve mainly. I have a feeling if you continue running your tires without alignment then it would end up having wear on the face in side of tire. That's just my two cents.

 

I have had this a number of times. Some sidewalls are just weak and roll slightly giving you a washout feeling. I have nankang ns1s on a car that did this, and a set of nitto nt450s that were fine at first but something happened to the sidewall after a few autocrosses and the car felt like a death trap.
Worn out trailing arm bushings can magnify this problem.
It surprises me to hear falkens having this issue. but who knows.
I have always loved kumhos for their rock hard sidewall

 

It also depends on the road. If you're driving on a concrete hwy, sometimes the grooves can cause the car to "shimmy" from side to side. At least out here in LA, the freeway is part of the problem. It's not always the car (My car has Yokos)

 

Are the falkens brand new? Had a similar issue with a brand new set of bridgestones and the tires just needed to be broken in(according to me that is). Car felt really sketchy and the rear end would dance excessively(more than I felt it should) under heavy braking, but after I abused them a bit in a controlled enviroment they were fine. I chocked it up to them needing to be heat cycled once or twice. Something tell's me that probably wasn't the right way to go about addressing the issue, but at the time I was like "**** it, worth a try."

 

u r going to have to put some miles on them before they get their usual grip. Same thing happened to me when i got all new tires. After a hundred miles or so it was good to go.

 

i'm sorry, but what?

 

Removing the wheels doesn't mess up the alignment, as long as the mating surfaces are clean it shouldnt ever effect your alignment.

 

This. The crown of the road will cause that feeling.

 

As someone said early it is more of a side to side shimmy, quite scary during high speeds(100+). Put a couple more hundred miles on tonight as well as raised my rear ride height and it seems a little better now. All together about 400miles on the tires.

I'm deffinetly going to get a alignment soon. I can see the wear where the tire grips the road and the outside of the tire isnt wearing barley.

Thanks for the help!