D'Addario makes a heavy gauge string set with a 63 gauge bass E, but you have to special order it from a music store. I use a bastard set with the 63 bass, a GHS 50 A, and the rest are Martin SP mediums on my Martin, with no problem percieved after two years. I don't know what the tension numbers would be, but I love the bass from E down to C, and no fret buzz. Good Luck!