what is the purpose of the offset? i mean why does it need to exist at all? thanx for the help and the link.

 

Well, the offset determines how far in, or how far out the wheel sticks out of the fender. If you had a negative offset, meaning that the face of the wheel is towards the back of the wheel, the you'll have something like dayton's (lowrider wheels) and it would stick out way beyond your fender.

If you had a really high positive offset, then the face of the wheel would be toward the front of the wheel and when you mount them on your car, you probably wouldn't see the wheels if you were looking at the front of the car. Then you'd experience rubbing on the inside of your fenderwell.

The ideal offset for civics is generally around +40mm thru +45mm.