I'm a new owner of an 05 2500HD extcab DMAX.
She's Bone stock with 245's on it. What are the pro's and con's between putting 275's and 285's if they fit? I've heard that the 245's won't last to long, so I was looking at upgrading and putting the original 245's on some steel rims for winter driving.

285s will fit with minor trimming on the stock rims. (285/75-16) IMO the stock tires suck and I got them off my truck as soon as I could. After coming to a stopsign and just tapping my brakes in 2wd and them sending me on a 360, that was enough for me. I ran BFG All terrains this last winter and they did awesome! I have pics in my signature of what I had to do to get them to fit with little to no rubbing. Also, your speedo will be off by about 3-5 MPH at 65 (mine was verified with GPS) I would just recommend getting a good all terrain tire and running it year round.

Yeah once you run a 285 you won't ever put the 245s back on.