Time for new rear tires questions

255 is as wide as you can go on a Dart without moving the springs, and then only if your backspacing is dead on. A 1/2" spring relocation should get you to 275, but that's it without a 3" relocation and mini-tub.

What you end up with for tires really depends on what you do with the car. I won't run BFG T/A's on anything I drive, but that's just me. A lot of folks don't like 17" or 18" rims either, but if you actually want good, street legal tires that's pretty much what you have to do.