[RiceBox]

My car had this crazy shimmy in the back when I was going slow and if I want over 100km/h (60mph) the car would vibrate so much!! Well I just got new tires and the car is soooo smoooth now!!! Got it up to 145 km/h (90 mph) and there was not one single vibration. It was a little noisy though, my tach was reading 4000RPM's.

 

[Nismodriver]

You probably had lost a balancing weight, or had uneven treadwear due to poor alignment, improper tire pressure, etc. These are all good things to check out regulalry to ensure long tire life and ride comfort, not to mention driver/passenger safety.
John

 

[RiceBox]

The balancing was fine. I did it twice. They also had the right amount of pressure. The problem was that the tires were from Walmart. (I didn't buy them, they came with the car)

 

[Nismodriver]

Oh yeah, I forgot that one, crappy tires, that'll do it. At any rate, glad to hear your baby is rollin smooth again!
John