The 2012 GMC Sierra 2500 HD 2wd Extended Cab bolt pattern is 8-180 mm. This means there are 8 lugs and the diameter of the circle that the lugs make up measures 180 mm or 7.08 inches across. To get a close measurement of your 8 lug bolt pattern without a bolt pattern tool you should measure from the center of one lug to the center of the lug across from it.
