The 2008 GMC Acadia SLE AWD bolt pattern is 6-132 mm. This means there are 6 lugs and the diameter of the circle that the lugs make up measures 132 mm or 5.2 inches across. To get a close measurement of your 6 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.
