The 1999 Dodge Durango Base Model bolt pattern is 6-114.3 mm. This means there are 6 lugs and the diameter of the circle that the lugs make up measures 114.3 mm or 4.5 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.
