I currently have the OEM Pirelli's size 255/40-19ZR which I have been happy with. I'm in Southern California so snow is a non-issue.

 

I have heard many good things about the Michelin Super Sports. When i replace my tires that's what i am going with! If you compare your OEM tires with these, you will be amazed and they are the same price.
Michelin Pilot Super Sport

 

Hey thanks for the information! They are rated very well but from the picture it looks like a really low profile tire. Do you know if it is identical to the OEM in that respect(side wall size)? I'm not real fond of the low profile tires and it makes the ride bumpy too!

 

The link JaguarXKR provided is for the same size tire you mentioned in your original post. The tire size does not vary by manufacturer like tread wear and traction ratings do. Some have a little bit different sidewall design with a rim protector or might look a little different, but the size is universal. With a 255/40R19, you have a tread width of 255mm, a sidewall height of 102mm and a 19" wheel. The "40" in the size refers to the sidewall height as a percentage of the width; meaning the sidewall height is 40% of the width.