just got a set of mickey thompson et street SS tires. 275/40/17 after doing a pull (only to 80-90mph), and i let off and hit the brakes, the *** end of the car feels very loose/floaty...anyone else ever experience this? just swapped from nt05's and it never happened before i swapped tires. scared the **** out of me the 1st time it happened

 

That's typical of tires with a soft sidewall. The fronts are stiff so the rears will feel like it's swaying around and getting rear wheel steering around turns. They are drag tires and should probably not be driven on the street; especially at low pressures.
You may need to run a lot more pressure near the tires max for more stability and air them down for the track.

 

ok thanks....i dont really drive the car on the street too much. i was just doing some tuning on my new ebc, did my first wot pull and wasnt expecting it. just wanted to make sure its normal...