Just replaced my stock Potenza RE-050 with Potenza RE-01R (same size). My car feels SLOW! Like the difference between empty and full tank times two.
Don't know yet about the handling, but the car just feel heavy now. Already played with tire pressure (not enough tho).

 

you put new tires on your car and now it feels slower? This is interesting.

Did you put a bunch of stuff in your trunk or eat a lot for dinner? yea i'm jk but your car shouldn't feel slower from new tires. I'm sure it's mental.

 

yeah there is no way that could make a noticable difference at all. BTW let me know how you like them, i got the same tires im waiting a couple more weeks to put them on and i cant wait!

 

well the tires are actually wider than the stock tires,...so you MAY feel a slight plowing feeling,...almost as if you are driving through a half inch of snow with the new tires,...i felt the same thing. you will get use to it

 

Put even more air in them (38 psi warm) and feels a little better. Yeah, fronts are over an inch wider (6.7"-8"). Also, tires are about 2lbs heavier (front and rear). If that rule is true (1lb on wheels = 10lbs in car), that's 80lbs. Maybe it's in my head, maybe not.
There is more grip. Before last addition of air, tires (rear) squealed around corner (getting back end loose). With added air they are quiet.

Oh, and to the smart ass: I did have a big lunch...

 

wait for about 500 miles and they wont "Squeal" around anything. be careful till then

 

New tires often feel slower until they break in, usually after about 500 miles. Since your older tires were worn, you had less tread and lower tread depth tires respond quicker. This is why racers will "shave" new tires.

 

I just put on z1 starspecs also, went up to 225/255, and my car also feels slower.

 

Ok, did some more driving tonight and I am getting a better feel for the handling difference (which is good, but different). I'll write more about it soon.

 

well i may be going from 225/255 to 215/245 soon. I'll feel faster? lol