my z has had this problem since i bought it. the wheel rubs on the fender when i am going fast and hit a good bump. it is worse when i have another person in the car. i thought the springs were weak so i got new ones. now thw problem is not as bad but it still happens. the springs lowerd the car by one inch. i have heard offset being thrown around. is that what might be the problem? my rims are offset too much? can i fix that with spacers? wouldnt spacers push them out further and make it worse? or could it be something else?

What size wheels and tires are you running? That's the key here.

the rear rubber is p215/60r14

the rims diameter from flange edge to edge is 15 1/4 inch and is about 7 inch wide