265 is a 10.5 inch cross section, at a 65 ratio on a 17 inch rim, would be approximately 30.5 inches tall overall, which is equivalent to a 31x10.50R17, 31x10.50 was stock size for some of the k1500s.
265/75R16 is 31.5 inches tall, equivalent to a 32x10.50R16
Being an inch shorter overall than what LTZ is running, you should have no issues unless your springs are really bad