[armyjordan]

I have a 2005 mustang gt 5spd manual. I just replaced my ball joints at work at 86,000 miles and also replaced my rear tires with what we have available at work, which are Firestone Bridgestone tires. Short story I put on Bridgestone Turanza Serenity plus tires and when I change lanes at highway speed it wants to almost oversteer and throw me almost into the wall. It feels like my rear end is sliding out although I know I still have plenty of traction (or should). Front end is tight, rear end is tight (as far as I can tell). I replaced my rear sway bar links 3 days after and the problem is still there.
Maybe rotate tires and try again? I have pretty stiff kuhmo lx platinums in the front.

 

[Jozsefsz]

What sized tires on what sized wheels? If the answer is stock on stock, and the pressures are good, maybe you have a shifted belt? If so the rotation could help determine where the problem is.

 

[armyjordan]

They are 235/55/17 but not stock wheels. They're tsw'. Not sure on the width, probably close to stock if not stock width. They are offset a bit (maybe half an inch). I've had them for 3 or 4 years now. The kuhmos speed rating is 103w and the turanza's is 99v. None of the tires have shifted belts. I checked them all at work. Its just strange. The turanzas are apparently rated for my car.

 

[mustang78248]

Swap the tires/wheels from front to back and see how it handles. The two pairs of tires you have are different enough that they may affect handling, but it shouldn't be a dramatic difference. If it really feels that out of control then there is something else that is not right.

Are you sure everything is set up right after the ball joint change? It sounds like the
steering geometry is off and you are getting oversteer.

Bruce