Driving me nuts

[moose666]

okay hey everybody this is my first time posting and it may seem like a silly problem but i just cant figure it out. okay i baught a 78 gmc shortbox stepside that was already lowered and as i am to understand it has 2.5" drop spindles with a 1" drop coil. my problem is it cam with some funky 70's mags on it so i baught a set of stock rally rims had them painted and wrapped with rubber. the problem began when i went to put them on the truck. they went on ok but when i let the truck off the jack and when to move the truck it cleared the wheel weights off and was digging the end of the a arm into the rim. i see tons of lowered trucks like mine running stock rims and i just cant figure out why mine are giving me so much trouble. the rims by the way are stock 15" by 8" wide with 4.5" backspacing. so any help with this is most appreciated