I’ve been thinking about going 255s just to make sure they stay inside the wheel well. I have air shocks on now but have experience with air shocks failing on my wedding day 42 years ago and eating the edges of the rear tires up on my Roadrunner.
They're a safer bet for sure, especially if you can't get your backspace matched up so your wheels are perfectly centered up. But 275's will fit most Barracuda's with the stock spring locations if the backspace centers the wheel up decently well. But body tolerances are definitely a consideration, you have to measure your car to be sure.
