I brought home a new 2015 GMC 2500hd this weekend. SLT, pretty well loaded and GORGEOUS! I love this thing! Traded in a '13 GMC that was an excellent truck, just boring. I never fell in love with...
Looks good. Not sure why your 15" would sit 2" higher unless your old truck was a 2-wheel drive. They are the same as the 11-14" truck just different body/cab