On a 9" wheel, a 255 or 265 would be better suited. With a 275, there will be a slight bulge in the sidewall. On a 10.5" wheel, you can use anywhere from a 275 to a 305. I hope you plan on running spacers, because those offsets are pretty weak.

Hey man I noticed you live near me, I'm in Tampa, work in Clearwater! I'm about to buy some rims for me Z and I've noticed you've been very insistent on a 275 front tire. I want to get as wide as possible in the front and rear without any rubbing. The wheels I'm looking at are a 20x9 with a 20mm offset and 20x10.5 with a 30mm offset. What is your thought? 275/30/20 and 305/25/20...I want to do what's best for handling, performance, and looks!
thanks!