Springs and pads question...Do I or Dont I?

Fellas, got a question, I am looking at putting Eibach sport springs spring on my car to lower it a bit, and from what I have been reading on here most of you guys have also changed your spring pads also, do I need to change my spring pads if I put the Eibach sport springs on? and also whay I have your attention, I am also looking at putting 19's on my ride also, my question their is Is their a recommended size tires for 19's or is it a matter of preference, I see most of you guys use 235's up front and 265's in the rear would it be fine to do like a 255 0r 245 in the rear?