tire sizes

Hello everyone, I need to replace my rear tires. I currently have Continental ExtremeContact DWS 06 Plus 255/35 R19 Fronts. I was wondering what size/spec rear Continental ExtremeContact DWS 06 Plus tires I should purchase. Currently on stock wheels with stock suspension, planning on lowering...

i'm deciding which tire and spring setup to run right now, i've been leaning towards eibach and running a 275/35 front and 305/30 rear but the h&r allows for a 305/35 in the rear. kinda torn right now so i'd like to hear some of your guys' opinions and pics or vids if you can thank you. ?? ps...