I mentioned in another thread that the back right tire on my mustang causes my car to shake when i get over 60. I think its just from the shop "fixing" the tire because it started a few weeks to a month after i got the car back. I would imagine that if it was a warped rotor it would shake all the time, right? I went looking on line at tires to replace the two back ones and i also need to know if the company Primewell makes a decent tire. Firestone has them on an online special for 60 bucks a tire and they are W rated ultra high performence tires.