picked up a 2500 slt c/c/ s/b 6.4 a little over a week ago and headed straight to grande prairie, with 4.10's and 115 the whole way i averaged 15.7/100k which i was really impressed with and it passes awesome definitely impressed and lots of smiles. next is seeing what it does pulling the enclosed.
the 275 is only 1cm wider and actually the same overall diameter as the 265's would be. they are just a more common tire dodge uses them on all of there newer half tons with 20's so the sidewall profiling should b almost exactly the same as what you have.
If its the duramax where at 2007 and...
i work at kal tire and have run the TBC XTX sports on everything there an awesome all terrain tire, there winter rated, 80K guarentee and ride awesome plus they have some really nice hard rubber budget mudders because they arent a big name. JMO