I had these on my Sapphire, and depending on the size, they suck in hard use. Basically the tyre wall is not of sufficient rigidity for track use. In high speed cornering the car moves around like the bushes are fucked. I "almost" changed my rear beam bushes as it was so disconcerting, but I then put the rear slicks I had on the car, and it went away. It was then that I realised it was the tyre and upon examination, this was evidenced by the wear on the sidewall .