I have 225/55 R17 in front with I believe about a 4" drop and its not even close. The rear is where I rubbed with 255/55R18 on the driver side fender lip, I radiused it and it still rubbed after having the under bed notch done last week, I believe it is down about 9", has been flipped, 1 " blocks and just added 2" shackles. So bought smaller tires 235/55 R 18 and its perfect, lotta trouble to get low but it sits perfect now, oh its a 1990 454SS BTW
Bobby V