Welcome to Challengertalk Sebastian. On the stock 8" wide wheels, 255/45 is the widest suggested size. People run 275/40s on the front with 9" and + wheels, with the right offset. They will also ft on the back. People have managed 315/35 on 10.5" on the back with the correct offset and tire make.
If your question was on the stock 8" wheels, moving from 245 to 255 will not net you much, and will further limit your overall tire choices.
In my opinion, the best thing you would get from the 255 is a bit of additional rim protection with a slightly wider bulge. If you are in need of tires, and the brand you want comes in 255, I can think of no reason not to get them over the 245.